From 6231c9e1a9f35b535c66709aa8a6eda40dbc4132 Mon Sep 17 00:00:00 2001 From: Prasad Pandit Date: Wed, 3 Jan 2024 13:23:43 +0530 Subject: KVM: x86: make KVM_REQ_NMI request iff NMI pending for vcpu kvm_vcpu_ioctl_x86_set_vcpu_events() routine makes 'KVM_REQ_NMI' request for a vcpu even when its 'events->nmi.pending' is zero. Ex: qemu_thread_start kvm_vcpu_thread_fn qemu_wait_io_event qemu_wait_io_event_common process_queued_cpu_work do_kvm_cpu_synchronize_post_init/_reset kvm_arch_put_registers kvm_put_vcpu_events (cpu, level=[2|3]) This leads vCPU threads in QEMU to constantly acquire & release the global mutex lock, delaying the guest boot due to lock contention. Add check to make KVM_REQ_NMI request only if vcpu has NMI pending. Fixes: bdedff263132 ("KVM: x86: Route pending NMIs from userspace through process_nmi()") Cc: stable@vger.kernel.org Signed-off-by: Prasad Pandit Link: https://lore.kernel.org/r/20240103075343.549293-1-ppandit@redhat.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 363b1c080205..25bc52cdf8f4 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5454,7 +5454,8 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu, if (events->flags & KVM_VCPUEVENT_VALID_NMI_PENDING) { vcpu->arch.nmi_pending = 0; atomic_set(&vcpu->arch.nmi_queued, events->nmi.pending); - kvm_make_request(KVM_REQ_NMI, vcpu); + if (events->nmi.pending) + kvm_make_request(KVM_REQ_NMI, vcpu); } static_call(kvm_x86_set_nmi_mask)(vcpu, events->nmi.masked); -- cgit v1.2.3 From 9e62797fd7e8eef9c8a3f7b54b57fbc9caf6a20a Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Tue, 9 Jan 2024 15:11:21 +0100 Subject: KVM: x86: Make gtod_is_based_on_tsc() return 'bool' gtod_is_based_on_tsc() is boolean in nature, i.e. it returns '1' for good clocksources and '0' otherwise. Moreover, its result is used raw by kvm_get_time_and_clockread()/kvm_get_walltime_and_clockread() which are 'bool'. No functional change intended. Signed-off-by: Vitaly Kuznetsov Link: https://lore.kernel.org/r/20240109141121.1619463-6-vkuznets@redhat.com Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 363b1c080205..aa27aec10860 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2507,7 +2507,7 @@ static u64 compute_guest_tsc(struct kvm_vcpu *vcpu, s64 kernel_ns) } #ifdef CONFIG_X86_64 -static inline int gtod_is_based_on_tsc(int mode) +static inline bool gtod_is_based_on_tsc(int mode) { return mode == VDSO_CLOCKMODE_TSC || mode == VDSO_CLOCKMODE_HVCLOCK; } -- cgit v1.2.3 From 05519c86d6997cfb9bb6c82ce1595d1015b718dc Mon Sep 17 00:00:00 2001 From: Mingwei Zhang Date: Tue, 23 Jan 2024 22:12:20 +0000 Subject: KVM: x86/pmu: Fix type length error when reading pmu->fixed_ctr_ctrl Use a u64 instead of a u8 when taking a snapshot of pmu->fixed_ctr_ctrl when reprogramming fixed counters, as truncating the value results in KVM thinking fixed counter 2 is already disabled (the bug also affects fixed counters 3+, but KVM doesn't yet support those). As a result, if the guest disables fixed counter 2, KVM will get a false negative and fail to reprogram/disable emulation of the counter, which can leads to incorrect counts and spurious PMIs in the guest. Fixes: 76d287b2342e ("KVM: x86/pmu: Drop "u8 ctrl, int idx" for reprogram_fixed_counter()") Cc: stable@vger.kernel.org Signed-off-by: Mingwei Zhang Link: https://lore.kernel.org/r/20240123221220.3911317-1-mizhang@google.com [sean: rewrite changelog to call out the effects of the bug] Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/pmu_intel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index a6216c874729..315c7c2ba89b 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -71,7 +71,7 @@ static int fixed_pmc_events[] = { static void reprogram_fixed_counters(struct kvm_pmu *pmu, u64 data) { struct kvm_pmc *pmc; - u8 old_fixed_ctr_ctrl = pmu->fixed_ctr_ctrl; + u64 old_fixed_ctr_ctrl = pmu->fixed_ctr_ctrl; int i; pmu->fixed_ctr_ctrl = data; -- cgit v1.2.3 From 3376ca3f1a2075eaa23c5576c47d04d7e8a4adda Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Sat, 3 Feb 2024 13:45:20 +0100 Subject: KVM: x86: Fix KVM_GET_MSRS stack info leak Commit 6abe9c1386e5 ("KVM: X86: Move ignore_msrs handling upper the stack") changed the 'ignore_msrs' handling, including sanitizing return values to the caller. This was fine until commit 12bc2132b15e ("KVM: X86: Do the same ignore_msrs check for feature msrs") which allowed non-existing feature MSRs to be ignored, i.e. to not generate an error on the ioctl() level. It even tried to preserve the sanitization of the return value. However, the logic is flawed, as '*data' will be overwritten again with the uninitialized stack value of msr.data. Fix this by simplifying the logic and always initializing msr.data, vanishing the need for an additional error exit path. Fixes: 12bc2132b15e ("KVM: X86: Do the same ignore_msrs check for feature msrs") Signed-off-by: Mathias Krause Reviewed-by: Xiaoyao Li Link: https://lore.kernel.org/r/20240203124522.592778-2-minipli@grsecurity.net Signed-off-by: Sean Christopherson --- arch/x86/kvm/x86.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 25bc52cdf8f4..3f6e82fd37f3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1704,22 +1704,17 @@ static int do_get_msr_feature(struct kvm_vcpu *vcpu, unsigned index, u64 *data) struct kvm_msr_entry msr; int r; + /* Unconditionally clear the output for simplicity */ + msr.data = 0; msr.index = index; r = kvm_get_msr_feature(&msr); - if (r == KVM_MSR_RET_INVALID) { - /* Unconditionally clear the output for simplicity */ - *data = 0; - if (kvm_msr_ignored_check(index, 0, false)) - r = 0; - } - - if (r) - return r; + if (r == KVM_MSR_RET_INVALID && kvm_msr_ignored_check(index, 0, false)) + r = 0; *data = msr.data; - return 0; + return r; } static bool __kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer) -- cgit v1.2.3