[PATCH v4 1/8] KVM: x86: nSVM: Clear VMCB_NPT clean bit when updating hPAT from guest mode

[Jim Mattson]

When running an L2 guest and writing to MSR_IA32_CR_PAT, the host PAT value
is stored in both vmcb01's g_pat field and vmcb02's g_pat field, but the
clean bit was only being cleared for vmcb02.

Introduce the helper vmcb_set_gpat() which sets vmcb->save.g_pat and marks
the VMCB dirty for VMCB_NPT. Use this helper in both svm_set_msr() for
updating vmcb01 and in nested_vmcb02_compute_g_pat() for updating vmcb02,
ensuring both VMCBs' NPT fields are properly marked dirty.

Fixes: 4995a3685f1b ("KVM: SVM: Use a separate vmcb for the nested L2 guest")
Signed-off-by: Jim Mattson <jmatt...@google.com>
---
 arch/x86/kvm/svm/nested.c | 2 +-
 arch/x86/kvm/svm/svm.c    | 3 +--
 arch/x86/kvm/svm/svm.h    | 9 +++++----
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index d80b1bde6630..b72a1f3c4144 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -707,7 +707,7 @@ void nested_vmcb02_compute_g_pat(struct vcpu_svm *svm)
                return;
 
        /* FIXME: merge g_pat from vmcb01 and vmcb12.  */
-       svm->nested.vmcb02.ptr->save.g_pat = svm->vmcb01.ptr->save.g_pat;
+       vmcb_set_gpat(svm->nested.vmcb02.ptr, svm->vmcb01.ptr->save.g_pat);
 }
 
 static void nested_vmcb02_prepare_save(struct vcpu_svm *svm)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 364915f42e13..529cbac57814 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2924,10 +2924,9 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct 
msr_data *msr)
                if (ret)
                        break;
 
-               svm->vmcb01.ptr->save.g_pat = data;
+               vmcb_set_gpat(svm->vmcb01.ptr, data);
                if (is_guest_mode(vcpu))
                        nested_vmcb02_compute_g_pat(svm);
-               vmcb_mark_dirty(svm->vmcb, VMCB_NPT);
                break;
        case MSR_IA32_SPEC_CTRL:
                if (!msr->host_initiated &&
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 0bb93879abfe..9850ed01e16e 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -434,14 +434,15 @@ static inline void vmcb_mark_dirty(struct vmcb *vmcb, int 
bit)
        vmcb->control.clean &= ~(1 << bit);
 }
 
-static inline bool vmcb_is_dirty(struct vmcb *vmcb, int bit)
+static inline bool vmcb12_is_dirty(struct vmcb_ctrl_area_cached *control, int 
bit)
 {
-        return !test_bit(bit, (unsigned long *)&vmcb->control.clean);
+       return !test_bit(bit, (unsigned long *)&control->clean);
 }
 
-static inline bool vmcb12_is_dirty(struct vmcb_ctrl_area_cached *control, int 
bit)
+static inline void vmcb_set_gpat(struct vmcb *vmcb, u64 data)
 {
-       return !test_bit(bit, (unsigned long *)&control->clean);
+       vmcb->save.g_pat = data;
+       vmcb_mark_dirty(vmcb, VMCB_NPT);
 }
 
 static __always_inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
-- 
2.53.0.239.g8d8fc8a987-goog