[PATCH v10 6/9] KVM: x86: Introduce get_untagged_addr() in kvm_x86_ops and call it in emulator

[Binbin Wu]

Introduce a new interface get_untagged_addr() to kvm_x86_ops to untag
the metadata from linear address.  Call the interface in linearization
of instruction emulator for 64-bit mode.

When enabled feature like Intel Linear Address Masking or AMD Upper Address
Ignore, linear address may be tagged with metadata. Linear address should be
checked for modified canonicality and untagged in instruction emulator.

Introduce get_untagged_addr() to kvm_x86_ops to hide the vendor specific code.
Pass the 'flags' to allow vendor specific implementation to precisely identify
the access type.

Signed-off-by: Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx>
Tested-by: Xuelian Guo <xuelian.guo@xxxxxxxxx>
Reviewed-by: Chao Gao <chao.gao@xxxxxxxxx>
---
 arch/x86/include/asm/kvm-x86-ops.h |  1 +
 arch/x86/include/asm/kvm_host.h    |  2 ++
 arch/x86/kvm/emulate.c             |  2 +-
 arch/x86/kvm/kvm_emulate.h         |  3 +++
 arch/x86/kvm/x86.c                 | 10 ++++++++++
 5 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index 13bc212cd4bc..052652073a4b 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -133,6 +133,7 @@ KVM_X86_OP(msr_filter_changed)
 KVM_X86_OP(complete_emulated_msr)
 KVM_X86_OP(vcpu_deliver_sipi_vector)
 KVM_X86_OP_OPTIONAL_RET0(vcpu_get_apicv_inhibit_reasons);
+KVM_X86_OP(get_untagged_addr)
 
 #undef KVM_X86_OP
 #undef KVM_X86_OP_OPTIONAL
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 881a0be862e1..36267ee7806a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1743,6 +1743,8 @@ struct kvm_x86_ops {
 	 * Returns vCPU specific APICv inhibit reasons
 	 */
 	unsigned long (*vcpu_get_apicv_inhibit_reasons)(struct kvm_vcpu *vcpu);
+
+	gva_t (*get_untagged_addr)(struct kvm_vcpu *vcpu, gva_t gva, unsigned int flags);
 };
 
 struct kvm_x86_nested_ops {
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 9b4b3ce6d52a..25983ebd95fa 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -701,7 +701,7 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
 	*max_size = 0;
 	switch (mode) {
 	case X86EMUL_MODE_PROT64:
-		*linear = la;
+		*linear = la = ctxt->ops->get_untagged_addr(ctxt, la, flags);
 		va_bits = ctxt_virt_addr_bits(ctxt);
 		if (!__is_canonical_address(la, va_bits))
 			goto bad;
diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
index c944055091e1..790cf2dea75b 100644
--- a/arch/x86/kvm/kvm_emulate.h
+++ b/arch/x86/kvm/kvm_emulate.h
@@ -232,6 +232,9 @@ struct x86_emulate_ops {
 	int (*leave_smm)(struct x86_emulate_ctxt *ctxt);
 	void (*triple_fault)(struct x86_emulate_ctxt *ctxt);
 	int (*set_xcr)(struct x86_emulate_ctxt *ctxt, u32 index, u64 xcr);
+
+	gva_t (*get_untagged_addr)(struct x86_emulate_ctxt *ctxt, gva_t addr,
+				   unsigned int flags);
 };
 
 /* Type, address-of, and value of an instruction's operand. */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6a6d08238e8d..339a113b45af 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8300,6 +8300,15 @@ static void emulator_vm_bugged(struct x86_emulate_ctxt *ctxt)
 		kvm_vm_bugged(kvm);
 }
 
+static gva_t emulator_get_untagged_addr(struct x86_emulate_ctxt *ctxt,
+					gva_t addr, unsigned int flags)
+{
+	if (!kvm_x86_ops.get_untagged_addr)
+		return addr;
+
+	return static_call(kvm_x86_get_untagged_addr)(emul_to_vcpu(ctxt), addr, flags);
+}
+
 static const struct x86_emulate_ops emulate_ops = {
 	.vm_bugged           = emulator_vm_bugged,
 	.read_gpr            = emulator_read_gpr,
@@ -8345,6 +8354,7 @@ static const struct x86_emulate_ops emulate_ops = {
 	.leave_smm           = emulator_leave_smm,
 	.triple_fault        = emulator_triple_fault,
 	.set_xcr             = emulator_set_xcr,
+	.get_untagged_addr   = emulator_get_untagged_addr,
 };
 
 static void toggle_interruptibility(struct kvm_vcpu *vcpu, u32 mask)
-- 
2.25.1