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author | Linus Torvalds <torvalds@linux-foundation.org> | 2022-08-05 00:59:54 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-08-05 00:59:54 +0300 |
commit | 7c5c3a6177fa9646884114fc7f2e970b0bc50dc9 (patch) | |
tree | 956857522574ae7cb07d2227dc16e53d7e9e00e7 /virt/kvm/pfncache.c | |
parent | f0a892f599c46af673e47418c47c15e69a7b67f4 (diff) | |
parent | 281106f938d3daaea6f8b6723a8217a2a1ef6936 (diff) | |
download | linux-7c5c3a6177fa9646884114fc7f2e970b0bc50dc9.tar.xz |
Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull kvm updates from Paolo Bonzini:
"Quite a large pull request due to a selftest API overhaul and some
patches that had come in too late for 5.19.
ARM:
- Unwinder implementations for both nVHE modes (classic and
protected), complete with an overflow stack
- Rework of the sysreg access from userspace, with a complete rewrite
of the vgic-v3 view to allign with the rest of the infrastructure
- Disagregation of the vcpu flags in separate sets to better track
their use model.
- A fix for the GICv2-on-v3 selftest
- A small set of cosmetic fixes
RISC-V:
- Track ISA extensions used by Guest using bitmap
- Added system instruction emulation framework
- Added CSR emulation framework
- Added gfp_custom flag in struct kvm_mmu_memory_cache
- Added G-stage ioremap() and iounmap() functions
- Added support for Svpbmt inside Guest
s390:
- add an interface to provide a hypervisor dump for secure guests
- improve selftests to use TAP interface
- enable interpretive execution of zPCI instructions (for PCI
passthrough)
- First part of deferred teardown
- CPU Topology
- PV attestation
- Minor fixes
x86:
- Permit guests to ignore single-bit ECC errors
- Intel IPI virtualization
- Allow getting/setting pending triple fault with
KVM_GET/SET_VCPU_EVENTS
- PEBS virtualization
- Simplify PMU emulation by just using PERF_TYPE_RAW events
- More accurate event reinjection on SVM (avoid retrying
instructions)
- Allow getting/setting the state of the speaker port data bit
- Refuse starting the kvm-intel module if VM-Entry/VM-Exit controls
are inconsistent
- "Notify" VM exit (detect microarchitectural hangs) for Intel
- Use try_cmpxchg64 instead of cmpxchg64
- Ignore benign host accesses to PMU MSRs when PMU is disabled
- Allow disabling KVM's "MONITOR/MWAIT are NOPs!" behavior
- Allow NX huge page mitigation to be disabled on a per-vm basis
- Port eager page splitting to shadow MMU as well
- Enable CMCI capability by default and handle injected UCNA errors
- Expose pid of vcpu threads in debugfs
- x2AVIC support for AMD
- cleanup PIO emulation
- Fixes for LLDT/LTR emulation
- Don't require refcounted "struct page" to create huge SPTEs
- Miscellaneous cleanups:
- MCE MSR emulation
- Use separate namespaces for guest PTEs and shadow PTEs bitmasks
- PIO emulation
- Reorganize rmap API, mostly around rmap destruction
- Do not workaround very old KVM bugs for L0 that runs with nesting enabled
- new selftests API for CPUID
Generic:
- Fix races in gfn->pfn cache refresh; do not pin pages tracked by
the cache
- new selftests API using struct kvm_vcpu instead of a (vm, id)
tuple"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (606 commits)
selftests: kvm: set rax before vmcall
selftests: KVM: Add exponent check for boolean stats
selftests: KVM: Provide descriptive assertions in kvm_binary_stats_test
selftests: KVM: Check stat name before other fields
KVM: x86/mmu: remove unused variable
RISC-V: KVM: Add support for Svpbmt inside Guest/VM
RISC-V: KVM: Use PAGE_KERNEL_IO in kvm_riscv_gstage_ioremap()
RISC-V: KVM: Add G-stage ioremap() and iounmap() functions
KVM: Add gfp_custom flag in struct kvm_mmu_memory_cache
RISC-V: KVM: Add extensible CSR emulation framework
RISC-V: KVM: Add extensible system instruction emulation framework
RISC-V: KVM: Factor-out instruction emulation into separate sources
RISC-V: KVM: move preempt_disable() call in kvm_arch_vcpu_ioctl_run
RISC-V: KVM: Make kvm_riscv_guest_timer_init a void function
RISC-V: KVM: Fix variable spelling mistake
RISC-V: KVM: Improve ISA extension by using a bitmap
KVM, x86/mmu: Fix the comment around kvm_tdp_mmu_zap_leafs()
KVM: SVM: Dump Virtual Machine Save Area (VMSA) to klog
KVM: x86/mmu: Treat NX as a valid SPTE bit for NPT
KVM: x86: Do not block APIC write for non ICR registers
...
Diffstat (limited to 'virt/kvm/pfncache.c')
-rw-r--r-- | virt/kvm/pfncache.c | 231 |
1 files changed, 150 insertions, 81 deletions
diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c index dd84676615f1..ab519f72f2cd 100644 --- a/virt/kvm/pfncache.c +++ b/virt/kvm/pfncache.c @@ -95,48 +95,143 @@ bool kvm_gfn_to_pfn_cache_check(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, } EXPORT_SYMBOL_GPL(kvm_gfn_to_pfn_cache_check); -static void __release_gpc(struct kvm *kvm, kvm_pfn_t pfn, void *khva, gpa_t gpa) +static void gpc_unmap_khva(struct kvm *kvm, kvm_pfn_t pfn, void *khva) { - /* Unmap the old page if it was mapped before, and release it */ - if (!is_error_noslot_pfn(pfn)) { - if (khva) { - if (pfn_valid(pfn)) - kunmap(pfn_to_page(pfn)); + /* Unmap the old pfn/page if it was mapped before. */ + if (!is_error_noslot_pfn(pfn) && khva) { + if (pfn_valid(pfn)) + kunmap(pfn_to_page(pfn)); #ifdef CONFIG_HAS_IOMEM - else - memunmap(khva); + else + memunmap(khva); #endif - } - - kvm_release_pfn(pfn, false); } } -static kvm_pfn_t hva_to_pfn_retry(struct kvm *kvm, unsigned long uhva) +static inline bool mmu_notifier_retry_cache(struct kvm *kvm, unsigned long mmu_seq) { + /* + * mn_active_invalidate_count acts for all intents and purposes + * like mmu_notifier_count here; but the latter cannot be used + * here because the invalidation of caches in the mmu_notifier + * event occurs _before_ mmu_notifier_count is elevated. + * + * Note, it does not matter that mn_active_invalidate_count + * is not protected by gpc->lock. It is guaranteed to + * be elevated before the mmu_notifier acquires gpc->lock, and + * isn't dropped until after mmu_notifier_seq is updated. + */ + if (kvm->mn_active_invalidate_count) + return true; + + /* + * Ensure mn_active_invalidate_count is read before + * mmu_notifier_seq. This pairs with the smp_wmb() in + * mmu_notifier_invalidate_range_end() to guarantee either the + * old (non-zero) value of mn_active_invalidate_count or the + * new (incremented) value of mmu_notifier_seq is observed. + */ + smp_rmb(); + return kvm->mmu_notifier_seq != mmu_seq; +} + +static kvm_pfn_t hva_to_pfn_retry(struct kvm *kvm, struct gfn_to_pfn_cache *gpc) +{ + /* Note, the new page offset may be different than the old! */ + void *old_khva = gpc->khva - offset_in_page(gpc->khva); + kvm_pfn_t new_pfn = KVM_PFN_ERR_FAULT; + void *new_khva = NULL; unsigned long mmu_seq; - kvm_pfn_t new_pfn; - int retry; + + lockdep_assert_held(&gpc->refresh_lock); + + lockdep_assert_held_write(&gpc->lock); + + /* + * Invalidate the cache prior to dropping gpc->lock, the gpa=>uhva + * assets have already been updated and so a concurrent check() from a + * different task may not fail the gpa/uhva/generation checks. + */ + gpc->valid = false; do { mmu_seq = kvm->mmu_notifier_seq; smp_rmb(); + write_unlock_irq(&gpc->lock); + + /* + * If the previous iteration "failed" due to an mmu_notifier + * event, release the pfn and unmap the kernel virtual address + * from the previous attempt. Unmapping might sleep, so this + * needs to be done after dropping the lock. Opportunistically + * check for resched while the lock isn't held. + */ + if (new_pfn != KVM_PFN_ERR_FAULT) { + /* + * Keep the mapping if the previous iteration reused + * the existing mapping and didn't create a new one. + */ + if (new_khva != old_khva) + gpc_unmap_khva(kvm, new_pfn, new_khva); + + kvm_release_pfn_clean(new_pfn); + + cond_resched(); + } + /* We always request a writeable mapping */ - new_pfn = hva_to_pfn(uhva, false, NULL, true, NULL); + new_pfn = hva_to_pfn(gpc->uhva, false, NULL, true, NULL); if (is_error_noslot_pfn(new_pfn)) - break; + goto out_error; + + /* + * Obtain a new kernel mapping if KVM itself will access the + * pfn. Note, kmap() and memremap() can both sleep, so this + * too must be done outside of gpc->lock! + */ + if (gpc->usage & KVM_HOST_USES_PFN) { + if (new_pfn == gpc->pfn) { + new_khva = old_khva; + } else if (pfn_valid(new_pfn)) { + new_khva = kmap(pfn_to_page(new_pfn)); +#ifdef CONFIG_HAS_IOMEM + } else { + new_khva = memremap(pfn_to_hpa(new_pfn), PAGE_SIZE, MEMREMAP_WB); +#endif + } + if (!new_khva) { + kvm_release_pfn_clean(new_pfn); + goto out_error; + } + } + + write_lock_irq(&gpc->lock); + + /* + * Other tasks must wait for _this_ refresh to complete before + * attempting to refresh. + */ + WARN_ON_ONCE(gpc->valid); + } while (mmu_notifier_retry_cache(kvm, mmu_seq)); + + gpc->valid = true; + gpc->pfn = new_pfn; + gpc->khva = new_khva + (gpc->gpa & ~PAGE_MASK); - KVM_MMU_READ_LOCK(kvm); - retry = mmu_notifier_retry_hva(kvm, mmu_seq, uhva); - KVM_MMU_READ_UNLOCK(kvm); - if (!retry) - break; + /* + * Put the reference to the _new_ pfn. The pfn is now tracked by the + * cache and can be safely migrated, swapped, etc... as the cache will + * invalidate any mappings in response to relevant mmu_notifier events. + */ + kvm_release_pfn_clean(new_pfn); - cond_resched(); - } while (1); + return 0; - return new_pfn; +out_error: + write_lock_irq(&gpc->lock); + + return -EFAULT; } int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, @@ -146,9 +241,7 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, unsigned long page_offset = gpa & ~PAGE_MASK; kvm_pfn_t old_pfn, new_pfn; unsigned long old_uhva; - gpa_t old_gpa; void *old_khva; - bool old_valid; int ret = 0; /* @@ -158,13 +251,18 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, if (page_offset + len > PAGE_SIZE) return -EINVAL; + /* + * If another task is refreshing the cache, wait for it to complete. + * There is no guarantee that concurrent refreshes will see the same + * gpa, memslots generation, etc..., so they must be fully serialized. + */ + mutex_lock(&gpc->refresh_lock); + write_lock_irq(&gpc->lock); - old_gpa = gpc->gpa; old_pfn = gpc->pfn; old_khva = gpc->khva - offset_in_page(gpc->khva); old_uhva = gpc->uhva; - old_valid = gpc->valid; /* If the userspace HVA is invalid, refresh that first */ if (gpc->gpa != gpa || gpc->generation != slots->generation || @@ -177,64 +275,17 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, gpc->uhva = gfn_to_hva_memslot(gpc->memslot, gfn); if (kvm_is_error_hva(gpc->uhva)) { - gpc->pfn = KVM_PFN_ERR_FAULT; ret = -EFAULT; goto out; } - - gpc->uhva += page_offset; } /* * If the userspace HVA changed or the PFN was already invalid, * drop the lock and do the HVA to PFN lookup again. */ - if (!old_valid || old_uhva != gpc->uhva) { - unsigned long uhva = gpc->uhva; - void *new_khva = NULL; - - /* Placeholders for "hva is valid but not yet mapped" */ - gpc->pfn = KVM_PFN_ERR_FAULT; - gpc->khva = NULL; - gpc->valid = true; - - write_unlock_irq(&gpc->lock); - - new_pfn = hva_to_pfn_retry(kvm, uhva); - if (is_error_noslot_pfn(new_pfn)) { - ret = -EFAULT; - goto map_done; - } - - if (gpc->usage & KVM_HOST_USES_PFN) { - if (new_pfn == old_pfn) { - new_khva = old_khva; - old_pfn = KVM_PFN_ERR_FAULT; - old_khva = NULL; - } else if (pfn_valid(new_pfn)) { - new_khva = kmap(pfn_to_page(new_pfn)); -#ifdef CONFIG_HAS_IOMEM - } else { - new_khva = memremap(pfn_to_hpa(new_pfn), PAGE_SIZE, MEMREMAP_WB); -#endif - } - if (new_khva) - new_khva += page_offset; - else - ret = -EFAULT; - } - - map_done: - write_lock_irq(&gpc->lock); - if (ret) { - gpc->valid = false; - gpc->pfn = KVM_PFN_ERR_FAULT; - gpc->khva = NULL; - } else { - /* At this point, gpc->valid may already have been cleared */ - gpc->pfn = new_pfn; - gpc->khva = new_khva; - } + if (!gpc->valid || old_uhva != gpc->uhva) { + ret = hva_to_pfn_retry(kvm, gpc); } else { /* If the HVA→PFN mapping was already valid, don't unmap it. */ old_pfn = KVM_PFN_ERR_FAULT; @@ -242,9 +293,26 @@ int kvm_gfn_to_pfn_cache_refresh(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, } out: + /* + * Invalidate the cache and purge the pfn/khva if the refresh failed. + * Some/all of the uhva, gpa, and memslot generation info may still be + * valid, leave it as is. + */ + if (ret) { + gpc->valid = false; + gpc->pfn = KVM_PFN_ERR_FAULT; + gpc->khva = NULL; + } + + /* Snapshot the new pfn before dropping the lock! */ + new_pfn = gpc->pfn; + write_unlock_irq(&gpc->lock); - __release_gpc(kvm, old_pfn, old_khva, old_gpa); + mutex_unlock(&gpc->refresh_lock); + + if (old_pfn != new_pfn) + gpc_unmap_khva(kvm, old_pfn, old_khva); return ret; } @@ -254,14 +322,13 @@ void kvm_gfn_to_pfn_cache_unmap(struct kvm *kvm, struct gfn_to_pfn_cache *gpc) { void *old_khva; kvm_pfn_t old_pfn; - gpa_t old_gpa; + mutex_lock(&gpc->refresh_lock); write_lock_irq(&gpc->lock); gpc->valid = false; old_khva = gpc->khva - offset_in_page(gpc->khva); - old_gpa = gpc->gpa; old_pfn = gpc->pfn; /* @@ -272,8 +339,9 @@ void kvm_gfn_to_pfn_cache_unmap(struct kvm *kvm, struct gfn_to_pfn_cache *gpc) gpc->pfn = KVM_PFN_ERR_FAULT; write_unlock_irq(&gpc->lock); + mutex_unlock(&gpc->refresh_lock); - __release_gpc(kvm, old_pfn, old_khva, old_gpa); + gpc_unmap_khva(kvm, old_pfn, old_khva); } EXPORT_SYMBOL_GPL(kvm_gfn_to_pfn_cache_unmap); @@ -286,6 +354,7 @@ int kvm_gfn_to_pfn_cache_init(struct kvm *kvm, struct gfn_to_pfn_cache *gpc, if (!gpc->active) { rwlock_init(&gpc->lock); + mutex_init(&gpc->refresh_lock); gpc->khva = NULL; gpc->pfn = KVM_PFN_ERR_FAULT; |