On Fri, Jul 05, 2013 at 11:13:17PM +0800, Arthur Chunqi Li wrote:
> Fix read/write to IA32_FEATURE_CONTROL MSR in nested environment.
>
> This patch simulate this MSR in nested_vmx and the default value is
> 0x0. BIOS should set it to 0x5 before VMXON. After setting the lock
> bit, write to it will cause #GP(0).
>
> Signed-off-by: Arthur Chunqi Li <yzt356@xxxxxxxxx>
The patch is heavily based on Nadav's one. You need to preserve
authorship. Add From: and Nadav's Sign-off-by.
> ---
> arch/x86/kvm/vmx.c | 25 +++++++++++++++++++++----
> arch/x86/kvm/x86.c | 3 ++-
> 2 files changed, 23 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 260a919..5e3d44e 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -373,6 +373,7 @@ struct nested_vmx {
> * we must keep them pinned while L2 runs.
> */
> struct page *apic_access_page;
> + u64 msr_ia32_feature_control;
> };
>
> #define POSTED_INTR_ON 0
> @@ -2277,8 +2278,11 @@ static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata)
>
> switch (msr_index) {
> case MSR_IA32_FEATURE_CONTROL:
> - *pdata = 0;
> - break;
> + if (nested_vmx_allowed(vcpu)){
> + *pdata = to_vmx(vcpu)->nested.msr_ia32_feature_control;
> + break;
> + }
> + return 0;
> case MSR_IA32_VMX_BASIC:
> /*
> * This MSR reports some information about VMX support. We
> @@ -2356,9 +2360,13 @@ static int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
> if (!nested_vmx_allowed(vcpu))
> return 0;
>
> - if (msr_index == MSR_IA32_FEATURE_CONTROL)
> - /* TODO: the right thing. */
> + if (msr_index == MSR_IA32_FEATURE_CONTROL){
> + if (to_vmx(vcpu)->nested.msr_ia32_feature_control
> + & FEATURE_CONTROL_LOCKED)
> + return 0;
> + to_vmx(vcpu)->nested.msr_ia32_feature_control = data;
You need to allow setting it from userspace, otherwise reset will not
clear it.
> return 1;
> + }
> /*
> * No need to treat VMX capability MSRs specially: If we don't handle
> * them, handle_wrmsr will #GP(0), which is correct (they are readonly)
> @@ -5595,6 +5603,15 @@ static int handle_vmon(struct kvm_vcpu *vcpu)
> skip_emulated_instruction(vcpu);
> return 1;
> }
> +
> +#define VMXON_NEEDED_FEATURES \
Avi asked to use const u64 here.
> + (FEATURE_CONTROL_LOCKED | FEATURE_CONTROL_VMXON_ENABLED_OUTSIDE_SMX)
> + if ((vmx->nested.msr_ia32_feature_control & VMXON_NEEDED_FEATURES)
> + != VMXON_NEEDED_FEATURES) {
> + kvm_inject_gp(vcpu, 0);
> + return 1;
> + }
> +
> if (enable_shadow_vmcs) {
> shadow_vmcs = alloc_vmcs();
> if (!shadow_vmcs)
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index e8ba99c..2d4eb8e 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -850,7 +850,8 @@ static u32 msrs_to_save[] = {
> #ifdef CONFIG_X86_64
> MSR_CSTAR, MSR_KERNEL_GS_BASE, MSR_SYSCALL_MASK, MSR_LSTAR,
> #endif
> - MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA
> + MSR_IA32_TSC, MSR_IA32_CR_PAT, MSR_VM_HSAVE_PA,
> + MSR_IA32_FEATURE_CONTROL
> };
>
> static unsigned num_msrs_to_save;
> --
> 1.7.9.5
--
Gleb.
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