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

Maxim Levitsky
2022-07-21T11:54:55Z

On Thu, 2022-07-21 at 00:18 +0000, Sean Christopherson wrote:
> 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?

Yes to some extent, patch was small so I didn't bother, but I don't mind splitting it up.

Best regards,
Maxim Levitsky

>
> > +
> > + 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];