KVM: x86: Introduce get_untagged_addr() in kvm_x86_ops and call it in emulator

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 (LAM) or AMD Upper
Address Ignore (UAI), linear addresses may be tagged with metadata that
needs to be dropped prior to canonicality checks, i.e. the metadata is
ignored.

Introduce get_untagged_addr() to kvm_x86_ops to hide the vendor specific
code, as sadly LAM and UAI have different semantics.  Pass the emulator
flags to allow vendor specific implementation to precisely identify the
access type (LAM doesn't untag certain accesses).

Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-9-binbin.wu@linux.intel.com
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: Binbin Wu

arch/x86/include/asm/kvm-x86-ops.h

@@ -135,6 +135,7 @@ 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_OPTIONAL(get_untagged_addr)
 
 #undef KVM_X86_OP
 #undef KVM_X86_OP_OPTIONAL

arch/x86/include/asm/kvm_host.h

@@ -1762,6 +1762,8 @@ 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 {

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;

arch/x86/kvm/kvm_emulate.h

@@ -230,6 +230,9 @@ 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. */

arch/x86/kvm/x86.c

@@ -8445,6 +8445,15 @@ 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,
@@ -8489,6 +8498,7 @@ 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)