diff options
| author | Sean Christopherson <seanjc@google.com> | 2021-05-04 10:17:24 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-05-19 10:13:16 +0200 |
| commit | 31f29749ee970c251b3a7e5b914108425940d089 (patch) | |
| tree | 179b3009eb64ae9752c87534a025ba6bad883030 /arch | |
| parent | 79abde761e05ea1cb5996d458c0d31f0d80813f1 (diff) | |
KVM: VMX: Disable preemption when probing user return MSRs
commit 5104d7ffcf24749939bea7fdb5378d186473f890 upstream.
Disable preemption when probing a user return MSR via RDSMR/WRMSR. If
the MSR holds a different value per logical CPU, the WRMSR could corrupt
the host's value if KVM is preempted between the RDMSR and WRMSR, and
then rescheduled on a different CPU.
Opportunistically land the helper in common x86, SVM will use the helper
in a future commit.
Fixes: 4be534102624 ("KVM: VMX: Initialize vmx->guest_msrs[] right after allocation")
Cc: stable@vger.kernel.org
Cc: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210504171734.1434054-6-seanjc@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/kvm_host.h | 1 | ||||
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 5 | ||||
| -rw-r--r-- | arch/x86/kvm/x86.c | 16 |
3 files changed, 18 insertions, 4 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 128d57b35574..ef56780022c3 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1668,6 +1668,7 @@ int kvm_pv_send_ipi(struct kvm *kvm, unsigned long ipi_bitmap_low, unsigned long icr, int op_64_bit); void kvm_define_user_return_msr(unsigned index, u32 msr); +int kvm_probe_user_return_msr(u32 msr); int kvm_set_user_return_msr(unsigned index, u64 val, u64 mask); u64 kvm_scale_tsc(struct kvm_vcpu *vcpu, u64 tsc); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 03393c0bdf59..d7f8d2167fda 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6864,12 +6864,9 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu) for (i = 0; i < ARRAY_SIZE(vmx_uret_msrs_list); ++i) { u32 index = vmx_uret_msrs_list[i]; - u32 data_low, data_high; int j = vmx->nr_uret_msrs; - if (rdmsr_safe(index, &data_low, &data_high) < 0) - continue; - if (wrmsr_safe(index, data_low, data_high) < 0) + if (kvm_probe_user_return_msr(index)) continue; vmx->guest_uret_msrs[j].slot = i; diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 39ab3d78bf57..c071a83d543a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -322,6 +322,22 @@ static void kvm_on_user_return(struct user_return_notifier *urn) } } +int kvm_probe_user_return_msr(u32 msr) +{ + u64 val; + int ret; + + preempt_disable(); + ret = rdmsrl_safe(msr, &val); + if (ret) + goto out; + ret = wrmsrl_safe(msr, val); +out: + preempt_enable(); + return ret; +} +EXPORT_SYMBOL_GPL(kvm_probe_user_return_msr); + void kvm_define_user_return_msr(unsigned slot, u32 msr) { BUG_ON(slot >= KVM_MAX_NR_USER_RETURN_MSRS); |