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2018-10-27Revert "mm, mmu_notifier: annotate mmu notifiers with blockable invalidate ↵Michal Hocko1-1/+0
callbacks" Revert 5ff7091f5a2ca ("mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks"). MMU_INVALIDATE_DOES_NOT_BLOCK flags was the only one used and it is no longer needed since 93065ac753e4 ("mm, oom: distinguish blockable mode for mmu notifiers"). We now have a full support for per range !blocking behavior so we can drop the stop gap workaround which the per notifier flag was used for. Link: http://lkml.kernel.org/r/20180827112623.8992-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Cc: David Rientjes <rientjes@google.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-10-26Merge tag 'kvm-4.20-1' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds7-120/+125
Pull KVM updates from Radim Krčmář: "ARM: - Improved guest IPA space support (32 to 52 bits) - RAS event delivery for 32bit - PMU fixes - Guest entry hardening - Various cleanups - Port of dirty_log_test selftest PPC: - Nested HV KVM support for radix guests on POWER9. The performance is much better than with PR KVM. Migration and arbitrary level of nesting is supported. - Disable nested HV-KVM on early POWER9 chips that need a particular hardware bug workaround - One VM per core mode to prevent potential data leaks - PCI pass-through optimization - merge ppc-kvm topic branch and kvm-ppc-fixes to get a better base s390: - Initial version of AP crypto virtualization via vfio-mdev - Improvement for vfio-ap - Set the host program identifier - Optimize page table locking x86: - Enable nested virtualization by default - Implement Hyper-V IPI hypercalls - Improve #PF and #DB handling - Allow guests to use Enlightened VMCS - Add migration selftests for VMCS and Enlightened VMCS - Allow coalesced PIO accesses - Add an option to perform nested VMCS host state consistency check through hardware - Automatic tuning of lapic_timer_advance_ns - Many fixes, minor improvements, and cleanups" * tag 'kvm-4.20-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (204 commits) KVM/nVMX: Do not validate that posted_intr_desc_addr is page aligned Revert "kvm: x86: optimize dr6 restore" KVM: PPC: Optimize clearing TCEs for sparse tables x86/kvm/nVMX: tweak shadow fields selftests/kvm: add missing executables to .gitignore KVM: arm64: Safety check PSTATE when entering guest and handle IL KVM: PPC: Book3S HV: Don't use streamlined entry path on early POWER9 chips arm/arm64: KVM: Enable 32 bits kvm vcpu events support arm/arm64: KVM: Rename function kvm_arch_dev_ioctl_check_extension() KVM: arm64: Fix caching of host MDCR_EL2 value KVM: VMX: enable nested virtualization by default KVM/x86: Use 32bit xor to clear registers in svm.c kvm: x86: Introduce KVM_CAP_EXCEPTION_PAYLOAD kvm: vmx: Defer setting of DR6 until #DB delivery kvm: x86: Defer setting of CR2 until #PF delivery kvm: x86: Add payload operands to kvm_multiple_exception kvm: x86: Add exception payload fields to kvm_vcpu_events kvm: x86: Add has_payload and payload to kvm_queued_exception KVM: Documentation: Fix omission in struct kvm_vcpu_events KVM: selftests: add Enlightened VMCS test ...
2018-10-24Merge branch 'siginfo-linus' of ↵Linus Torvalds1-10/+4
git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull siginfo updates from Eric Biederman: "I have been slowly sorting out siginfo and this is the culmination of that work. The primary result is in several ways the signal infrastructure has been made less error prone. The code has been updated so that manually specifying SEND_SIG_FORCED is never necessary. The conversion to the new siginfo sending functions is now complete, which makes it difficult to send a signal without filling in the proper siginfo fields. At the tail end of the patchset comes the optimization of decreasing the size of struct siginfo in the kernel from 128 bytes to about 48 bytes on 64bit. The fundamental observation that enables this is by definition none of the known ways to use struct siginfo uses the extra bytes. This comes at the cost of a small user space observable difference. For the rare case of siginfo being injected into the kernel only what can be copied into kernel_siginfo is delivered to the destination, the rest of the bytes are set to 0. For cases where the signal and the si_code are known this is safe, because we know those bytes are not used. For cases where the signal and si_code combination is unknown the bits that won't fit into struct kernel_siginfo are tested to verify they are zero, and the send fails if they are not. I made an extensive search through userspace code and I could not find anything that would break because of the above change. If it turns out I did break something it will take just the revert of a single change to restore kernel_siginfo to the same size as userspace siginfo. Testing did reveal dependencies on preferring the signo passed to sigqueueinfo over si->signo, so bit the bullet and added the complexity necessary to handle that case. Testing also revealed bad things can happen if a negative signal number is passed into the system calls. Something no sane application will do but something a malicious program or a fuzzer might do. So I have fixed the code that performs the bounds checks to ensure negative signal numbers are handled" * 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (80 commits) signal: Guard against negative signal numbers in copy_siginfo_from_user32 signal: Guard against negative signal numbers in copy_siginfo_from_user signal: In sigqueueinfo prefer sig not si_signo signal: Use a smaller struct siginfo in the kernel signal: Distinguish between kernel_siginfo and siginfo signal: Introduce copy_siginfo_from_user and use it's return value signal: Remove the need for __ARCH_SI_PREABLE_SIZE and SI_PAD_SIZE signal: Fail sigqueueinfo if si_signo != sig signal/sparc: Move EMT_TAGOVF into the generic siginfo.h signal/unicore32: Use force_sig_fault where appropriate signal/unicore32: Generate siginfo in ucs32_notify_die signal/unicore32: Use send_sig_fault where appropriate signal/arc: Use force_sig_fault where appropriate signal/arc: Push siginfo generation into unhandled_exception signal/ia64: Use force_sig_fault where appropriate signal/ia64: Use the force_sig(SIGSEGV,...) in ia64_rt_sigreturn signal/ia64: Use the generic force_sigsegv in setup_frame signal/arm/kvm: Use send_sig_mceerr signal/arm: Use send_sig_fault where appropriate signal/arm: Use force_sig_fault where appropriate ...
2018-10-22Merge tag 'arm64-upstream' of ↵Linus Torvalds1-2/+2
git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux Pull arm64 updates from Catalin Marinas: "Apart from some new arm64 features and clean-ups, this also contains the core mmu_gather changes for tracking the levels of the page table being cleared and a minor update to the generic compat_sys_sigaltstack() introducing COMPAT_SIGMINSKSZ. Summary: - Core mmu_gather changes which allow tracking the levels of page-table being cleared together with the arm64 low-level flushing routines - Support for the new ARMv8.5 PSTATE.SSBS bit which can be used to mitigate Spectre-v4 dynamically without trapping to EL3 firmware - Introduce COMPAT_SIGMINSTKSZ for use in compat_sys_sigaltstack - Optimise emulation of MRS instructions to ID_* registers on ARMv8.4 - Support for Common Not Private (CnP) translations allowing threads of the same CPU to share the TLB entries - Accelerated crc32 routines - Move swapper_pg_dir to the rodata section - Trap WFI instruction executed in user space - ARM erratum 1188874 workaround (arch_timer) - Miscellaneous fixes and clean-ups" * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (78 commits) arm64: KVM: Guests can skip __install_bp_hardening_cb()s HYP work arm64: cpufeature: Trap CTR_EL0 access only where it is necessary arm64: cpufeature: Fix handling of CTR_EL0.IDC field arm64: cpufeature: ctr: Fix cpu capability check for late CPUs Documentation/arm64: HugeTLB page implementation arm64: mm: Use __pa_symbol() for set_swapper_pgd() arm64: Add silicon-errata.txt entry for ARM erratum 1188873 Revert "arm64: uaccess: implement unsafe accessors" arm64: mm: Drop the unused cpu parameter MAINTAINERS: fix bad sdei paths arm64: mm: Use #ifdef for the __PAGETABLE_P?D_FOLDED defines arm64: Fix typo in a comment in arch/arm64/mm/kasan_init.c arm64: xen: Use existing helper to check interrupt status arm64: Use daifflag_restore after bp_hardening arm64: daifflags: Use irqflags functions for daifflags arm64: arch_timer: avoid unused function warning arm64: Trap WFI executed in userspace arm64: docs: Document SSBS HWCAP arm64: docs: Fix typos in ELF hwcaps arm64/kprobes: remove an extra semicolon in arch_prepare_kprobe ...
2018-10-19Merge tag 'kvmarm-for-v4.20' of ↵Paolo Bonzini5-102/+92
git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD KVM/arm updates for 4.20 - Improved guest IPA space support (32 to 52 bits) - RAS event delivery for 32bit - PMU fixes - Guest entry hardening - Various cleanups
2018-10-18arm/arm64: KVM: Enable 32 bits kvm vcpu events supportDongjiu Geng1-0/+1
The commit 539aee0edb9f ("KVM: arm64: Share the parts of get/set events useful to 32bit") shares the get/set events helper for arm64 and arm32, but forgot to share the cap extension code. User space will check whether KVM supports vcpu events by checking the KVM_CAP_VCPU_EVENTS extension Acked-by: James Morse <james.morse@arm.com> Reviewed-by : Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-10-18arm/arm64: KVM: Rename function kvm_arch_dev_ioctl_check_extension()Dongjiu Geng1-1/+1
Rename kvm_arch_dev_ioctl_check_extension() to kvm_arch_vm_ioctl_check_extension(), because it does not have any relationship with device. Renaming this function can make code readable. Cc: James Morse <james.morse@arm.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-10-17KVM: arm64: Fix caching of host MDCR_EL2 valueMark Rutland1-2/+2
At boot time, KVM stashes the host MDCR_EL2 value, but only does this when the kernel is not running in hyp mode (i.e. is non-VHE). In these cases, the stashed value of MDCR_EL2.HPMN happens to be zero, which can lead to CONSTRAINED UNPREDICTABLE behaviour. Since we use this value to derive the MDCR_EL2 value when switching to/from a guest, after a guest have been run, the performance counters do not behave as expected. This has been observed to result in accesses via PMXEVTYPER_EL0 and PMXEVCNTR_EL0 not affecting the relevant counters, resulting in events not being counted. In these cases, only the fixed-purpose cycle counter appears to work as expected. Fix this by always stashing the host MDCR_EL2 value, regardless of VHE. Cc: Christopher Dall <christoffer.dall@arm.com> Cc: James Morse <james.morse@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: stable@vger.kernel.org Fixes: 1e947bad0b63b351 ("arm64: KVM: Skip HYP setup when already running in HYP") Tested-by: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-10-17KVM: refine the comment of function gfn_to_hva_memslot_prot()Wei Yang1-2/+6
The original comment is little hard to understand. No functional change, just amend the comment a little. Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-10-17kvm/x86 : add coalesced pio supportPeng Hao2-3/+11
Coalesced pio is based on coalesced mmio and can be used for some port like rtc port, pci-host config port and so on. Specially in case of rtc as coalesced pio, some versions of windows guest access rtc frequently because of rtc as system tick. guest access rtc like this: write register index to 0x70, then write or read data from 0x71. writing 0x70 port is just as index and do nothing else. So we can use coalesced pio to handle this scene to reduce VM-EXIT time. When starting and closing a virtual machine, it will access pci-host config port frequently. So setting these port as coalesced pio can reduce startup and shutdown time. without my patch, get the vm-exit time of accessing rtc 0x70 and piix 0xcf8 using perf tools: (guest OS : windows 7 64bit) IO Port Access Samples Samples% Time% Min Time Max Time Avg time 0x70:POUT 86 30.99% 74.59% 9us 29us 10.75us (+- 3.41%) 0xcf8:POUT 1119 2.60% 2.12% 2.79us 56.83us 3.41us (+- 2.23%) with my patch IO Port Access Samples Samples% Time% Min Time Max Time Avg time 0x70:POUT 106 32.02% 29.47% 0us 10us 1.57us (+- 7.38%) 0xcf8:POUT 1065 1.67% 0.28% 0.41us 65.44us 0.66us (+- 10.55%) Signed-off-by: Peng Hao <peng.hao2@zte.com.cn> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-10-17KVM: leverage change to adjust slots->used_slots in update_memslots()Wei Yang1-9/+14
update_memslots() is only called by __kvm_set_memory_region(), in which "change" is calculated and indicates how to adjust slots->used_slots * increase by one if it is KVM_MR_CREATE * decrease by one if it is KVM_MR_DELETE * not change for others This patch adjusts slots->used_slots in update_memslots() based on "change" value instead of re-calculate those states again. Signed-off-by: Wei Yang <richard.weiyang@gmail.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-10-17KVM: x86: hyperv: optimize 'all cpus' case in kvm_hv_flush_tlb()Vitaly Kuznetsov1-4/+2
We can use 'NULL' to represent 'all cpus' case in kvm_make_vcpus_request_mask() and avoid building vCPU mask with all vCPUs. Suggested-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Roman Kagan <rkagan@virtuozzo.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-10-03KVM: arm/arm64: Ensure only THP is candidate for adjustmentPunit Agrawal1-1/+7
PageTransCompoundMap() returns true for hugetlbfs and THP hugepages. This behaviour incorrectly leads to stage 2 faults for unsupported hugepage sizes (e.g., 64K hugepage with 4K pages) to be treated as THP faults. Tighten the check to filter out hugetlbfs pages. This also leads to consistently mapping all unsupported hugepage sizes as PTE level entries at stage 2. Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Reviewed-by: Suzuki Poulose <suzuki.poulose@arm.com> Cc: Christoffer Dall <christoffer.dall@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: stable@vger.kernel.org # v4.13+ Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-10-03KVM: arm64: Drop __cpu_init_stage2 on the VHE pathMarc Zyngier1-8/+2
__cpu_init_stage2 doesn't do anything anymore on arm64, and is totally non-sensical if running VHE (as VHE is 64bit only). Reviewed-by: Eric Auger <eric.auger@redhat.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-10-03KVM: arm/arm64: Rename kvm_arm_config_vm to kvm_arm_setup_stage2Marc Zyngier1-1/+1
VM tends to be a very overloaded term in KVM, so let's keep it to describe the virtual machine. For the virtual memory setup, let's use the "stage2" suffix. Reviewed-by: Eric Auger <eric.auger@redhat.com> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-10-03kvm: arm64: Set a limit on the IPA sizeSuzuki K Poulose1-0/+2
So far we have restricted the IPA size of the VM to the default value (40bits). Now that we can manage the IPA size per VM and support dynamic stage2 page tables, we can allow VMs to have larger IPA. This patch introduces a the maximum IPA size supported on the host. This is decided by the following factors : 1) Maximum PARange supported by the CPUs - This can be inferred from the system wide safe value. 2) Maximum PA size supported by the host kernel (48 vs 52) 3) Number of levels in the host page table (as we base our stage2 tables on the host table helpers). Since the stage2 page table code is dependent on the stage1 page table, we always ensure that : Number of Levels at Stage1 >= Number of Levels at Stage2 So we limit the IPA to make sure that the above condition is satisfied. This will affect the following combinations of VA_BITS and IPA for different page sizes. Host configuration | Unsupported IPA ranges 39bit VA, 4K | [44, 48] 36bit VA, 16K | [41, 48] 42bit VA, 64K | [47, 52] Supporting the above combinations need independent stage2 page table manipulation code, which would need substantial changes. We could purse the solution independently and switch the page table code once we have it ready. Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Christoffer Dall <cdall@kernel.org> Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-10-01vgic: Add support for 52bit guest physical addressKristina Martsenko2-28/+10
Add support for handling 52bit guest physical address to the VGIC layer. So far we have limited the guest physical address to 48bits, by explicitly masking the upper bits. This patch removes the restriction. We do not have to check if the host supports 52bit as the gpa is always validated during an access. (e.g, kvm_{read/write}_guest, kvm_is_visible_gfn()). Also, the ITS table save-restore is also not affected with the enhancement. The DTE entries already store the bits[51:8] of the ITT_addr (with a 256byte alignment). Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Christoffer Dall <cdall@kernel.org> Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Kristina Martsenko <kristina.martsenko@arm.com> [ Macro clean ups, fix PROPBASER and PENDBASER accesses ] Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-10-01kvm: arm/arm64: Prepare for VM specific stage2 translationsSuzuki K Poulose3-60/+63
Right now the stage2 page table for a VM is hard coded, assuming an IPA of 40bits. As we are about to add support for per VM IPA, prepare the stage2 page table helpers to accept the kvm instance to make the right decision for the VM. No functional changes. Adds stage2_pgd_size(kvm) to replace S2_PGD_SIZE. Also, moves some of the definitions in arm32 to align with the arm64. Also drop the _AC() specifier constants wherever possible. Cc: Christoffer Dall <cdall@kernel.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-10-01kvm: arm/arm64: Allow arch specific configurations for VMSuzuki K Poulose1-2/+3
Allow the arch backends to perform VM specific initialisation. This will be later used to handle IPA size configuration and per-VM VTCR configuration on arm64. Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Christoffer Dall <cdall@kernel.org> Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-10-01kvm: arm/arm64: Remove spurious WARN_ONSuzuki K Poulose1-1/+1
On a 4-level page table pgd entry can be empty, unlike a 3-level page table. Remove the spurious WARN_ON() in stage_get_pud(). Acked-by: Christoffer Dall <cdall@kernel.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-10-01kvm: arm/arm64: Fix stage2_flush_memslot for 4 level page tableSuzuki K Poulose1-1/+2
So far we have only supported 3 level page table with fixed IPA of 40bits, where PUD is folded. With 4 level page tables, we need to check if the PUD entry is valid or not. Fix stage2_flush_memslot() to do this check, before walking down the table. Acked-by: Christoffer Dall <cdall@kernel.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-09-27signal/arm/kvm: Use send_sig_mceerrEric W. Biederman1-10/+4
This simplifies the code making it clearer what is going on, and making the siginfo generation easier to maintain. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-09-18arm64: KVM: Enable Common Not Private translationsVladimir Murzin1-2/+2
We rely on cpufeature framework to detect and enable CNP so for KVM we need to patch hyp to set CNP bit just before TTBR0_EL2 gets written. For the guest we encode CNP bit while building vttbr, so we don't need to bother with that in a world switch. Reviewed-by: James Morse <james.morse@arm.com> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2018-09-07KVM: Remove obsolete kvm_unmap_hva notifier backendMarc Zyngier2-27/+0
kvm_unmap_hva is long gone, and we only have kvm_unmap_hva_range to deal with. Drop the now obsolete code. Fixes: fb1522e099f0 ("KVM: update to new mmu_notifier semantic v2") Cc: James Hogan <jhogan@kernel.org> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
2018-09-07KVM: arm/arm64: Clean dcache to PoC when changing PTE due to CoWMarc Zyngier1-1/+8
When triggering a CoW, we unmap the RO page via an MMU notifier (invalidate_range_start), and then populate the new PTE using another one (change_pte). In the meantime, we'll have copied the old page into the new one. The problem is that the data for the new page is sitting in the cache, and should the guest have an uncached mapping to that page (or its MMU off), following accesses will bypass the cache. In a way, this is similar to what happens on a translation fault: We need to clean the page to the PoC before mapping it. So let's just do that. This fixes a KVM unit test regression observed on a HiSilicon platform, and subsequently reproduced on Seattle. Fixes: a9c0e12ebee5 ("KVM: arm/arm64: Only clean the dcache on translation fault") Cc: stable@vger.kernel.org # v4.16+ Reported-by: Mike Galbraith <efault@gmx.de> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
2018-08-22Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds14-109/+413
Pull second set of KVM updates from Paolo Bonzini: "ARM: - Support for Group0 interrupts in guests - Cache management optimizations for ARMv8.4 systems - Userspace interface for RAS - Fault path optimization - Emulated physical timer fixes - Random cleanups x86: - fixes for L1TF - a new test case - non-support for SGX (inject the right exception in the guest) - fix lockdep false positive" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (49 commits) KVM: VMX: fixes for vmentry_l1d_flush module parameter kvm: selftest: add dirty logging test kvm: selftest: pass in extra memory when create vm kvm: selftest: include the tools headers kvm: selftest: unify the guest port macros tools: introduce test_and_clear_bit KVM: x86: SVM: Call x86_spec_ctrl_set_guest/host() with interrupts disabled KVM: vmx: Inject #UD for SGX ENCLS instruction in guest KVM: vmx: Add defines for SGX ENCLS exiting x86/kvm/vmx: Fix coding style in vmx_setup_l1d_flush() x86: kvm: avoid unused variable warning KVM: Documentation: rename the capability of KVM_CAP_ARM_SET_SERROR_ESR KVM: arm/arm64: Skip updating PTE entry if no change KVM: arm/arm64: Skip updating PMD entry if no change KVM: arm: Use true and false for boolean values KVM: arm/arm64: vgic: Do not use spin_lock_irqsave/restore with irq disabled KVM: arm/arm64: vgic: Move DEBUG_SPINLOCK_BUG_ON to vgic.h KVM: arm: vgic-v3: Add support for ICC_SGI0R and ICC_ASGI1R accesses KVM: arm64: vgic-v3: Add support for ICC_SGI0R_EL1 and ICC_ASGI1R_EL1 accesses KVM: arm/arm64: vgic-v3: Add core support for Group0 SGIs ...
2018-08-22Merge branch 'akpm' (patches from Andrew)Linus Torvalds1-5/+10
Merge more updates from Andrew Morton: - the rest of MM - procfs updates - various misc things - more y2038 fixes - get_maintainer updates - lib/ updates - checkpatch updates - various epoll updates - autofs updates - hfsplus - some reiserfs work - fatfs updates - signal.c cleanups - ipc/ updates * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (166 commits) ipc/util.c: update return value of ipc_getref from int to bool ipc/util.c: further variable name cleanups ipc: simplify ipc initialization ipc: get rid of ids->tables_initialized hack lib/rhashtable: guarantee initial hashtable allocation lib/rhashtable: simplify bucket_table_alloc() ipc: drop ipc_lock() ipc/util.c: correct comment in ipc_obtain_object_check ipc: rename ipcctl_pre_down_nolock() ipc/util.c: use ipc_rcu_putref() for failues in ipc_addid() ipc: reorganize initialization of kern_ipc_perm.seq ipc: compute kern_ipc_perm.id under the ipc lock init/Kconfig: remove EXPERT from CHECKPOINT_RESTORE fs/sysv/inode.c: use ktime_get_real_seconds() for superblock stamp adfs: use timespec64 for time conversion kernel/sysctl.c: fix typos in comments drivers/rapidio/devices/rio_mport_cdev.c: remove redundant pointer md fork: don't copy inconsistent signal handler state to child signal: make get_signal() return bool signal: make sigkill_pending() return bool ...
2018-08-22mm, oom: distinguish blockable mode for mmu notifiersMichal Hocko1-5/+10
There are several blockable mmu notifiers which might sleep in mmu_notifier_invalidate_range_start and that is a problem for the oom_reaper because it needs to guarantee a forward progress so it cannot depend on any sleepable locks. Currently we simply back off and mark an oom victim with blockable mmu notifiers as done after a short sleep. That can result in selecting a new oom victim prematurely because the previous one still hasn't torn its memory down yet. We can do much better though. Even if mmu notifiers use sleepable locks there is no reason to automatically assume those locks are held. Moreover majority of notifiers only care about a portion of the address space and there is absolutely zero reason to fail when we are unmapping an unrelated range. Many notifiers do really block and wait for HW which is harder to handle and we have to bail out though. This patch handles the low hanging fruit. __mmu_notifier_invalidate_range_start gets a blockable flag and callbacks are not allowed to sleep if the flag is set to false. This is achieved by using trylock instead of the sleepable lock for most callbacks and continue as long as we do not block down the call chain. I think we can improve that even further because there is a common pattern to do a range lookup first and then do something about that. The first part can be done without a sleeping lock in most cases AFAICS. The oom_reaper end then simply retries if there is at least one notifier which couldn't make any progress in !blockable mode. A retry loop is already implemented to wait for the mmap_sem and this is basically the same thing. The simplest way for driver developers to test this code path is to wrap userspace code which uses these notifiers into a memcg and set the hard limit to hit the oom. This can be done e.g. after the test faults in all the mmu notifier managed memory and set the hard limit to something really small. Then we are looking for a proper process tear down. [akpm@linux-foundation.org: coding style fixes] [akpm@linux-foundation.org: minor code simplification] Link: http://lkml.kernel.org/r/20180716115058.5559-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Christian König <christian.koenig@amd.com> # AMD notifiers Acked-by: Leon Romanovsky <leonro@mellanox.com> # mlx and umem_odp Reported-by: David Rientjes <rientjes@google.com> Cc: "David (ChunMing) Zhou" <David1.Zhou@amd.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: David Airlie <airlied@linux.ie> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Cc: Rodrigo Vivi <rodrigo.vivi@intel.com> Cc: Doug Ledford <dledford@redhat.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Mike Marciniszyn <mike.marciniszyn@intel.com> Cc: Dennis Dalessandro <dennis.dalessandro@intel.com> Cc: Sudeep Dutt <sudeep.dutt@intel.com> Cc: Ashutosh Dixit <ashutosh.dixit@intel.com> Cc: Dimitri Sivanich <sivanich@sgi.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Jérôme Glisse" <jglisse@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Felix Kuehling <felix.kuehling@amd.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22Merge tag 'kvmarm-for-v4.19' of ↵Paolo Bonzini14-109/+413
git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD KVM/arm updates for 4.19 - Support for Group0 interrupts in guests - Cache management optimizations for ARMv8.4 systems - Userspace interface for RAS, allowing error retrival and injection - Fault path optimization - Emulated physical timer fixes - Random cleanups
2018-08-21Merge branch 'siginfo-linus' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull core signal handling updates from Eric Biederman: "It was observed that a periodic timer in combination with a sufficiently expensive fork could prevent fork from every completing. This contains the changes to remove the need for that restart. This set of changes is split into several parts: - The first part makes PIDTYPE_TGID a proper pid type instead something only for very special cases. The part starts using PIDTYPE_TGID enough so that in __send_signal where signals are actually delivered we know if the signal is being sent to a a group of processes or just a single process. - With that prep work out of the way the logic in fork is modified so that fork logically makes signals received while it is running appear to be received after the fork completes" * 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (22 commits) signal: Don't send signals to tasks that don't exist signal: Don't restart fork when signals come in. fork: Have new threads join on-going signal group stops fork: Skip setting TIF_SIGPENDING in ptrace_init_task signal: Add calculate_sigpending() fork: Unconditionally exit if a fatal signal is pending fork: Move and describe why the code examines PIDNS_ADDING signal: Push pid type down into complete_signal. signal: Push pid type down into __send_signal signal: Push pid type down into send_signal signal: Pass pid type into do_send_sig_info signal: Pass pid type into send_sigio_to_task & send_sigurg_to_task signal: Pass pid type into group_send_sig_info signal: Pass pid and pid type into send_sigqueue posix-timers: Noralize good_sigevent signal: Use PIDTYPE_TGID to clearly store where file signals will be sent pid: Implement PIDTYPE_TGID pids: Move the pgrp and session pid pointers from task_struct to signal_struct kvm: Don't open code task_pid in kvm_vcpu_ioctl pids: Compute task_tgid using signal->leader_pid ...
2018-08-19Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds1-14/+19
Pull first set of KVM updates from Paolo Bonzini: "PPC: - minor code cleanups x86: - PCID emulation and CR3 caching for shadow page tables - nested VMX live migration - nested VMCS shadowing - optimized IPI hypercall - some optimizations ARM will come next week" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (85 commits) kvm: x86: Set highest physical address bits in non-present/reserved SPTEs KVM/x86: Use CC_SET()/CC_OUT in arch/x86/kvm/vmx.c KVM: X86: Implement PV IPIs in linux guest KVM: X86: Add kvm hypervisor init time platform setup callback KVM: X86: Implement "send IPI" hypercall KVM/x86: Move X86_CR4_OSXSAVE check into kvm_valid_sregs() KVM: x86: Skip pae_root shadow allocation if tdp enabled KVM/MMU: Combine flushing remote tlb in mmu_set_spte() KVM: vmx: skip VMWRITE of HOST_{FS,GS}_BASE when possible KVM: vmx: skip VMWRITE of HOST_{FS,GS}_SEL when possible KVM: vmx: always initialize HOST_{FS,GS}_BASE to zero during setup KVM: vmx: move struct host_state usage to struct loaded_vmcs KVM: vmx: compute need to reload FS/GS/LDT on demand KVM: nVMX: remove a misleading comment regarding vmcs02 fields KVM: vmx: rename __vmx_load_host_state() and vmx_save_host_state() KVM: vmx: add dedicated utility to access guest's kernel_gs_base KVM: vmx: track host_state.loaded using a loaded_vmcs pointer KVM: vmx: refactor segmentation code in vmx_save_host_state() kvm: nVMX: Fix fault priority for VMX operations kvm: nVMX: Fix fault vector for VMX operation at CPL > 0 ...
2018-08-15Merge tag 'arm64-upstream' of ↵Linus Torvalds1-10/+10
git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux Pull arm64 updates from Will Deacon: "A bunch of good stuff in here. Worth noting is that we've pulled in the x86/mm branch from -tip so that we can make use of the core ioremap changes which allow us to put down huge mappings in the vmalloc area without screwing up the TLB. Much of the positive diffstat is because of the rseq selftest for arm64. Summary: - Wire up support for qspinlock, replacing our trusty ticket lock code - Add an IPI to flush_icache_range() to ensure that stale instructions fetched into the pipeline are discarded along with the I-cache lines - Support for the GCC "stackleak" plugin - Support for restartable sequences, plus an arm64 port for the selftest - Kexec/kdump support on systems booting with ACPI - Rewrite of our syscall entry code in C, which allows us to zero the GPRs on entry from userspace - Support for chained PMU counters, allowing 64-bit event counters to be constructed on current CPUs - Ensure scheduler topology information is kept up-to-date with CPU hotplug events - Re-enable support for huge vmalloc/IO mappings now that the core code has the correct hooks to use break-before-make sequences - Miscellaneous, non-critical fixes and cleanups" * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (90 commits) arm64: alternative: Use true and false for boolean values arm64: kexec: Add comment to explain use of __flush_icache_range() arm64: sdei: Mark sdei stack helper functions as static arm64, kaslr: export offset in VMCOREINFO ELF notes arm64: perf: Add cap_user_time aarch64 efi/libstub: Only disable stackleak plugin for arm64 arm64: drop unused kernel_neon_begin_partial() macro arm64: kexec: machine_kexec should call __flush_icache_range arm64: svc: Ensure hardirq tracing is updated before return arm64: mm: Export __sync_icache_dcache() for xen-privcmd drivers/perf: arm-ccn: Use devm_ioremap_resource() to map memory arm64: Add support for STACKLEAK gcc plugin arm64: Add stack information to on_accessible_stack drivers/perf: hisi: update the sccl_id/ccl_id when MT is supported arm64: fix ACPI dependencies rseq/selftests: Add support for arm64 arm64: acpi: fix alignment fault in accessing ACPI efi/arm: map UEFI memory map even w/o runtime services enabled efi/arm: preserve early mapping of UEFI memory map longer for BGRT drivers: acpi: add dependency of EFI for arm64 ...
2018-08-13KVM: arm/arm64: Skip updating PTE entry if no changePunit Agrawal1-0/+4
When there is contention on faulting in a particular page table entry at stage 2, the break-before-make requirement of the architecture can lead to additional refaulting due to TLB invalidation. Avoid this by skipping a page table update if the new value of the PTE matches the previous value. Cc: stable@vger.kernel.org Fixes: d5d8184d35c9 ("KVM: ARM: Memory virtualization setup") Reviewed-by: Suzuki Poulose <suzuki.poulose@arm.com> Acked-by: Christoffer Dall <christoffer.dall@arm.com> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-08-13KVM: arm/arm64: Skip updating PMD entry if no changePunit Agrawal1-11/+27
Contention on updating a PMD entry by a large number of vcpus can lead to duplicate work when handling stage 2 page faults. As the page table update follows the break-before-make requirement of the architecture, it can lead to repeated refaults due to clearing the entry and flushing the tlbs. This problem is more likely when - * there are large number of vcpus * the mapping is large block mapping such as when using PMD hugepages (512MB) with 64k pages. Fix this by skipping the page table update if there is no change in the entry being updated. Cc: stable@vger.kernel.org Fixes: ad361f093c1e ("KVM: ARM: Support hugetlbfs backed huge pages") Reviewed-by: Suzuki Poulose <suzuki.poulose@arm.com> Acked-by: Christoffer Dall <christoffer.dall@arm.com> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-08-12KVM: arm/arm64: vgic: Do not use spin_lock_irqsave/restore with irq disabledJia He3-12/+15
kvm_vgic_sync_hwstate is only called with IRQ being disabled. There is thus no need to call spin_lock_irqsave/restore in vgic_fold_lr_state and vgic_prune_ap_list. This patch replace them with the non irq-safe version. Signed-off-by: Jia He <jia.he@hxt-semitech.com> Acked-by: Christoffer Dall <christoffer.dall@arm.com> [maz: commit message tidy-up] Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-08-12KVM: arm/arm64: vgic: Move DEBUG_SPINLOCK_BUG_ON to vgic.hJia He2-6/+6
DEBUG_SPINLOCK_BUG_ON can be used with both vgic-v2 and vgic-v3, so let's move it to vgic.h Signed-off-by: Jia He <jia.he@hxt-semitech.com> [maz: commit message tidy-up] Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-08-12KVM: arm/arm64: vgic-v3: Add core support for Group0 SGIsMarc Zyngier1-4/+15
Although vgic-v3 now supports Group0 interrupts, it still doesn't deal with Group0 SGIs. As usually with the GIC, nothing is simple: - ICC_SGI1R can signal SGIs of both groups, since GICD_CTLR.DS==1 with KVM (as per 8.1.10, Non-secure EL1 access) - ICC_SGI0R can only generate Group0 SGIs - ICC_ASGI1R sees its scope refocussed to generate only Group0 SGIs (as per the note at the bottom of Table 8-14) We only support Group1 SGIs so far, so no material change. Reviewed-by: Eric Auger <eric.auger@redhat.com> Reviewed-by: Christoffer Dall <christoffer.dall@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-08-06KVM: try __get_user_pages_fast even if not in atomic contextPaolo Bonzini1-8/+6
We are currently cutting hva_to_pfn_fast short if we do not want an immediate exit, which is represented by !async && !atomic. However, this is unnecessary, and __get_user_pages_fast is *much* faster because the regular get_user_pages takes pmd_lock/pte_lock. In fact, when many CPUs take a nested vmexit at the same time the contention on those locks is visible, and this patch removes about 25% (compared to 4.18) from vmexit.flat on a 16 vCPU nested guest. Suggested-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-08-06KVM: x86: Add tlb remote flush callback in kvm_x86_ops.Tianyu Lan1-1/+2
This patch is to provide a way for platforms to register hv tlb remote flush callback and this helps to optimize operation of tlb flush among vcpus for nested virtualization case. Signed-off-by: Lan Tianyu <Tianyu.Lan@microsoft.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-08-06kvm: x86: Use fast CR3 switch for nested VMXJunaid Shahid1-4/+10
Use the fast CR3 switch mechanism to locklessly change the MMU root page when switching between L1 and L2. The switch from L2 to L1 should always go through the fast path, while the switch from L1 to L2 should go through the fast path if L1's CR3/EPTP for L2 hasn't changed since the last time. Signed-off-by: Junaid Shahid <junaids@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-08-06Merge tag 'v4.18-rc6' into HEADPaolo Bonzini1-6/+11
Pull bug fixes into the KVM development tree to avoid nasty conflicts.
2018-07-31KVM: arm/arm64: Fix lost IRQs from emulated physcial timer when blockedChristoffer Dall1-0/+5
When the VCPU is blocked (for example from WFI) we don't inject the physical timer interrupt if it should fire while the CPU is blocked, but instead we just wake up the VCPU and expect kvm_timer_vcpu_load to take care of injecting the interrupt. Unfortunately, kvm_timer_vcpu_load() doesn't actually do that, it only has support to schedule a soft timer if the emulated phys timer is expected to fire in the future. Follow the same pattern as kvm_timer_update_state() and update the irq state after potentially scheduling a soft timer. Reported-by: Andre Przywara <andre.przywara@arm.com> Cc: Stable <stable@vger.kernel.org> # 4.15+ Fixes: bbdd52cfcba29 ("KVM: arm/arm64: Avoid phys timer emulation in vcpu entry/exit") Signed-off-by: Christoffer Dall <christoffer.dall@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-07-31KVM: arm/arm64: Fix potential loss of ptimer interruptsChristoffer Dall1-5/+5
kvm_timer_update_state() is called when changing the phys timer configuration registers, either via vcpu reset, as a result of a trap from the guest, or when userspace programs the registers. phys_timer_emulate() is in turn called by kvm_timer_update_state() to either cancel an existing software timer, or program a new software timer, to emulate the behavior of a real phys timer, based on the change in configuration registers. Unfortunately, the interaction between these two functions left a small race; if the conceptual emulated phys timer should actually fire, but the soft timer hasn't executed its callback yet, we cancel the timer in phys_timer_emulate without injecting an irq. This only happens if the check in kvm_timer_update_state is called before the timer should fire, which is relatively unlikely, but possible. The solution is to update the state of the phys timer after calling phys_timer_emulate, which will pick up the pending timer state and update the interrupt value. Note that this leaves the opportunity of raising the interrupt twice, once in the just-programmed soft timer, and once in kvm_timer_update_state. Since this always happens synchronously with the VCPU execution, there is no harm in this, and the guest ever only sees a single timer interrupt. Cc: Stable <stable@vger.kernel.org> # 4.15+ Signed-off-by: Christoffer Dall <christoffer.dall@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-07-25Merge branch 'sched/urgent' into sched/core, to pick up fixesIngo Molnar1-6/+11
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-07-24KVM: arm/arm64: vgic: Fix possible spectre-v1 write in vgic_mmio_write_apr()Mark Rutland1-0/+3
It's possible for userspace to control n. Sanitize n when using it as an array index, to inhibit the potential spectre-v1 write gadget. Note that while it appears that n must be bound to the interval [0,3] due to the way it is extracted from addr, we cannot guarantee that compiler transformations (and/or future refactoring) will ensure this is the case, and given this is a slow path it's better to always perform the masking. Found by smatch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Christoffer Dall <christoffer.dall@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: kvmarm@lists.cs.columbia.edu Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-07-21kvm: Don't open code task_pid in kvm_vcpu_ioctlEric W. Biederman1-1/+1
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-07-21KVM: arm: Add 32bit get/set events supportJames Morse1-4/+0
arm64's new use of KVMs get_events/set_events API calls isn't just or RAS, it allows an SError that has been made pending by KVM as part of its device emulation to be migrated. Wire this up for 32bit too. We only need to read/write the HCR_VA bit, and check that no esr has been provided, as we don't yet support VDFSR. Signed-off-by: James Morse <james.morse@arm.com> Reviewed-by: Dongjiu Geng <gengdongjiu@huawei.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-07-21KVM: arm64: Share the parts of get/set events useful to 32bitJames Morse1-0/+28
The get/set events helpers to do some work to check reserved and padding fields are zero. This is useful on 32bit too. Move this code into virt/kvm/arm/arm.c, and give the arch code some underscores. This is temporarily hidden behind __KVM_HAVE_VCPU_EVENTS until 32bit is wired up. Signed-off-by: James Morse <james.morse@arm.com> Reviewed-by: Dongjiu Geng <gengdongjiu@huawei.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-07-21arm/arm64: KVM: Add KVM_GET/SET_VCPU_EVENTSDongjiu Geng1-0/+21
For the migrating VMs, user space may need to know the exception state. For example, in the machine A, KVM make an SError pending, when migrate to B, KVM also needs to pend an SError. This new IOCTL exports user-invisible states related to SError. Together with appropriate user space changes, user space can get/set the SError exception state to do migrate/snapshot/suspend. Signed-off-by: Dongjiu Geng <gengdongjiu@huawei.com> Reviewed-by: James Morse <james.morse@arm.com> [expanded documentation wording] Signed-off-by: James Morse <james.morse@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
2018-07-21KVM: arm/arm64: vgic: Let userspace opt-in to writable v2 IGROUPRChristoffer Dall1-1/+15
Simply letting IGROUPR be writable from userspace would break migration from old kernels to newer kernels, because old kernels incorrectly report interrupt groups as group 1. This would not be a big problem if userspace wrote GICD_IIDR as read from the kernel, because we could detect the incompatibility and return an error to userspace. Unfortunately, this is not the case with current userspace implementations and simply letting IGROUPR be writable from userspace for an emulated GICv2 silently breaks migration and causes the destination VM to no longer run after migration. We now encourage userspace to write the read and expected value of GICD_IIDR as the first part of a GIC register restore, and if we observe a write to GICD_IIDR we know that userspace has been updated and has had a chance to cope with older kernels (VGICv2 IIDR.Revision == 0) incorrectly reporting interrupts as group 1, and therefore we now allow groups to be user writable. Reviewed-by: Andrew Jones <drjones@redhat.com> Signed-off-by: Christoffer Dall <christoffer.dall@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>