[PATCH v4 8/9] KVM: x86: emulation: Apply LAM when emulating data access

Robert Hoo
2023-02-09T02:42:03Z

When in KVM emulation, calculated a LA for data access, apply LAM if
guest is at that moment LAM active, so that the following canonical check
can pass.

Signed-off-by: Robert Hoo <robert.hu@linux.intel.com>
---
arch/x86/kvm/emulate.c | 6 ++++++
arch/x86/kvm/x86.h | 13 +++++++++++++
2 files changed, 19 insertions(+)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 5cc3efa0e21c..d52037151133 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -700,6 +700,12 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
*max_size = 0;
switch (mode) {
case X86EMUL_MODE_PROT64:
+ /*
+ * LAM applies only on data access
+ */
+ if (!fetch && is_lam_active(ctxt->vcpu))
+ la = kvm_untagged_addr(la, ctxt->vcpu);
+
*linear = la;
va_bits = ctxt_virt_addr_bits(ctxt);
if (!__is_canonical_address(la, va_bits))
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 7228895d4a6f..9397e9f4e061 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -135,6 +135,19 @@ static inline int is_long_mode(struct kvm_vcpu *vcpu)
#endif
}

+#ifdef CONFIG_X86_64
+static inline bool is_lam_active(struct kvm_vcpu *vcpu)
+{
+ return kvm_read_cr3(vcpu) & (X86_CR3_LAM_U48 | X86_CR3_LAM_U57) ||
+ kvm_read_cr4_bits(vcpu, X86_CR4_LAM_SUP);
+}
+#else
+static inline bool is_lam_active(struct kvm_vcpu *vcpu)
+{
+ return false;
+}
+#endif
+
static inline bool is_64_bit_mode(struct kvm_vcpu *vcpu)
{
int cs_db, cs_l;
--
2.31.1