Re: [PATCH v2 10/11] KVM: x86: SVM: use smram structs

Sean Christopherson
2022-07-21T00:18:51Z

On Tue, Jun 21, 2022, Maxim Levitsky wrote:
> This removes the last user of put_smstate/GET_SMSTATE so
> remove these functions as well.
>
> Also add a sanity check that we don't attempt to enter the SMM
> on non long mode capable guest CPU with a running nested guest.
>
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
> arch/x86/include/asm/kvm_host.h | 6 ------
> arch/x86/kvm/svm/svm.c | 28 +++++++++++++++++-----------
> 2 files changed, 17 insertions(+), 17 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 1038ccb7056a39..9e8467be96b4e6 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -2057,12 +2057,6 @@ static inline int kvm_cpu_get_apicid(int mps_cpu)
> #endif
> }
>
> -#define put_smstate(type, buf, offset, val) \
> - *(type *)((buf) + (offset) - 0x7e00) = val
> -
> -#define GET_SMSTATE(type, buf, offset) \
> - (*(type *)((buf) + (offset) - 0x7e00))
> -
> int kvm_cpu_dirty_log_size(void);
>
> int memslot_rmap_alloc(struct kvm_memory_slot *slot, unsigned long npages);
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 136298cfb3fb57..8dcbbe839bef36 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -4399,6 +4399,7 @@ static int svm_smi_allowed(struct kvm_vcpu *vcpu, bool for_injection)
>
> static int svm_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
> {
> + struct kvm_smram_state_64 *smram = (struct kvm_smram_state_64 *)smstate;
> struct vcpu_svm *svm = to_svm(vcpu);
> struct kvm_host_map map_save;
> int ret;
> @@ -4406,10 +4407,17 @@ static int svm_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
> if (!is_guest_mode(vcpu))
> return 0;
>
> - /* FED8h - SVM Guest */
> - put_smstate(u64, smstate, 0x7ed8, 1);
> - /* FEE0h - SVM Guest VMCB Physical Address */
> - put_smstate(u64, smstate, 0x7ee0, svm->nested.vmcb12_gpa);
> + /*
> + * 32 bit SMRAM format doesn't preserve EFER and SVM state.
> + * SVM should not be enabled by the userspace without marking
> + * the CPU as at least long mode capable.
> + */
> +
> + if (!guest_cpuid_has(vcpu, X86_FEATURE_SVM))
> + return 1;

Isn't this is an independent bug fix? I.e. should be in its own patch?

> +
> + smram->svm_guest_flag = 1;
> + smram->svm_guest_vmcb_gpa = svm->nested.vmcb12_gpa;
>
> svm->vmcb->save.rax = vcpu->arch.regs[VCPU_REGS_RAX];
> svm->vmcb->save.rsp = vcpu->arch.regs[VCPU_REGS_RSP];