Il 20/04/2013 10:52, Jan Kiszka ha scritto:
> As we may emulate the loading of EFER on VM-entry and VM-exit, implement
> the checks that VMX performs on the guest and host values on vmlaunch/
> vmresume. Factor out kvm_valid_efer for this purpose which checks for
> set reserved bits.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
> ---
>
> Changes in v2:
> - refactored if clauses as requested by Paolo
> - fixed typo in comment found my Marcelo
>
> arch/x86/include/asm/kvm_host.h | 1 +
> arch/x86/kvm/vmx.c | 40 +++++++++++++++++++++++++++++++++++++++
> arch/x86/kvm/x86.c | 29 ++++++++++++++++++---------
> 3 files changed, 60 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 599f98b..18635ae 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -809,6 +809,7 @@ static inline int emulate_instruction(struct kvm_vcpu *vcpu,
> }
>
> void kvm_enable_efer_bits(u64);
> +bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);
> int kvm_get_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *data);
> int kvm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr);
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 19aebc7..e3b951f 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -7327,6 +7327,7 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> int cpu;
> struct loaded_vmcs *vmcs02;
> + bool ia32e;
>
> if (!nested_vmx_check_permission(vcpu) ||
> !nested_vmx_check_vmcs12(vcpu))
> @@ -7415,6 +7416,45 @@ static int nested_vmx_run(struct kvm_vcpu *vcpu, bool launch)
> }
>
> /*
> + * If the “load IA32_EFER” VM-entry control is 1, the following checks
> + * are performed on the field for the IA32_EFER MSR:
> + * - Bits reserved in the IA32_EFER MSR must be 0.
> + * - Bit 10 (corresponding to IA32_EFER.LMA) must equal the value of
> + * the IA-32e mode guest VM-exit control. It must also be identical
> + * to bit 8 (LME) if bit 31 in the CR0 field (corresponding to
> + * CR0.PG) is 1.
> + */
> + if (vmcs12->vm_entry_controls & VM_ENTRY_LOAD_IA32_EFER) {
> + ia32e = (vmcs12->vm_entry_controls & VM_ENTRY_IA32E_MODE) != 0;
> + if (!kvm_valid_efer(vcpu, vmcs12->guest_ia32_efer) ||
> + ia32e != !!(vmcs12->guest_ia32_efer & EFER_LMA) ||
> + ((vmcs12->guest_cr0 & X86_CR0_PG) &&
> + ia32e != !!(vmcs12->guest_ia32_efer & EFER_LME))) {
> + nested_vmx_entry_failure(vcpu, vmcs12,
> + EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
> + return 1;
> + }
> + }
> +
> + /*
> + * If the load IA32_EFER VM-exit control is 1, bits reserved in the
> + * IA32_EFER MSR must be 0 in the field for that register. In addition,
> + * the values of the LMA and LME bits in the field must each be that of
> + * the host address-space size VM-exit control.
> + */
> + if (vmcs12->vm_exit_controls & VM_EXIT_LOAD_IA32_EFER) {
> + ia32e = (vmcs12->vm_exit_controls &
> + VM_EXIT_HOST_ADDR_SPACE_SIZE) != 0;
> + if (!kvm_valid_efer(vcpu, vmcs12->host_ia32_efer) ||
> + ia32e != !!(vmcs12->host_ia32_efer & EFER_LMA) ||
> + ia32e != !!(vmcs12->host_ia32_efer & EFER_LME)) {
> + nested_vmx_entry_failure(vcpu, vmcs12,
> + EXIT_REASON_INVALID_STATE, ENTRY_FAIL_DEFAULT);
> + return 1;
> + }
> + }
Looks good, difficult to do better with C's operator precedence rules.
Paolo
> + /*
> * We're finally done with prerequisite checking, and can start with
> * the nested entry.
> */
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 50e2e10..482784d 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -845,23 +845,17 @@ static const u32 emulated_msrs[] = {
> MSR_IA32_MCG_CTL,
> };
>
> -static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
> +bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
> {
> - u64 old_efer = vcpu->arch.efer;
> -
> if (efer & efer_reserved_bits)
> - return 1;
> -
> - if (is_paging(vcpu)
> - && (vcpu->arch.efer & EFER_LME) != (efer & EFER_LME))
> - return 1;
> + return false;
>
> if (efer & EFER_FFXSR) {
> struct kvm_cpuid_entry2 *feat;
>
> feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
> if (!feat || !(feat->edx & bit(X86_FEATURE_FXSR_OPT)))
> - return 1;
> + return false;
> }
>
> if (efer & EFER_SVME) {
> @@ -869,9 +863,24 @@ static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
>
> feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
> if (!feat || !(feat->ecx & bit(X86_FEATURE_SVM)))
> - return 1;
> + return false;
> }
>
> + return true;
> +}
> +EXPORT_SYMBOL_GPL(kvm_valid_efer);
> +
> +static int set_efer(struct kvm_vcpu *vcpu, u64 efer)
> +{
> + u64 old_efer = vcpu->arch.efer;
> +
> + if (!kvm_valid_efer(vcpu, efer))
> + return 1;
> +
> + if (is_paging(vcpu)
> + && (vcpu->arch.efer & EFER_LME) != (efer & EFER_LME))
> + return 1;
> +
> efer &= ~EFER_LMA;
> efer |= vcpu->arch.efer & EFER_LMA;
>
>
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