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

Maxim Levitsky
2022-06-21T15:10:12Z

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;
+
+ 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];
@@ -4446,9 +4454,9 @@ static int svm_enter_smm(struct kvm_vcpu *vcpu, char *smstate)

static int svm_leave_smm(struct kvm_vcpu *vcpu, const 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, map_save;
- u64 saved_efer, vmcb12_gpa;
struct vmcb *vmcb12;
int ret;

@@ -4456,18 +4464,16 @@ static int svm_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
return 0;

/* Non-zero if SMI arrived while vCPU was in guest mode. */
- if (!GET_SMSTATE(u64, smstate, 0x7ed8))
+ if (!smram->svm_guest_flag)
return 0;

if (!guest_cpuid_has(vcpu, X86_FEATURE_SVM))
return 1;

- saved_efer = GET_SMSTATE(u64, smstate, 0x7ed0);
- if (!(saved_efer & EFER_SVME))
+ if (!(smram->efer & EFER_SVME))
return 1;

- vmcb12_gpa = GET_SMSTATE(u64, smstate, 0x7ee0);
- if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmcb12_gpa), &map) == -EINVAL)
+ if (kvm_vcpu_map(vcpu, gpa_to_gfn(smram->svm_guest_vmcb_gpa), &map) == -EINVAL)
return 1;

ret = 1;
@@ -4493,7 +4499,7 @@ static int svm_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
vmcb12 = map.hva;
nested_copy_vmcb_control_to_cache(svm, &vmcb12->control);
nested_copy_vmcb_save_to_cache(svm, &vmcb12->save);
- ret = enter_svm_guest_mode(vcpu, vmcb12_gpa, vmcb12, false);
+ ret = enter_svm_guest_mode(vcpu, smram->svm_guest_vmcb_gpa, vmcb12, false);

if (ret)
goto unmap_save;
--
2.26.3