KVM: x86: Add X86EMUL_F_MSR and X86EMUL_F_DT_LOAD to aid canonical checks

[ Upstream commit c534b37 ]

Add emulation flags for MSR accesses and Descriptor Tables loads, and pass
the new flags as appropriate to emul_is_noncanonical_address().  The flags
will be used to perform the correct canonical check, as the type of access
affects whether or not CR4.LA57 is consulted when determining the canonical
bit.

No functional change is intended.

Signed-off-by: Maxim Levitsky <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
[sean: split to separate patch, massage changelog]
Signed-off-by: Sean Christopherson <[email protected]>
Stable-dep-of: fa787ac ("KVM: x86/hyper-v: Skip non-canonical addresses during PV TLB flush")
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Maxim Levitsky

arch/x86/kvm/emulate.c

@@ -651,9 +651,10 @@ static inline u8 ctxt_virt_addr_bits(struct x86_emulate_ctxt *ctxt)
 }
 
 static inline bool emul_is_noncanonical_address(u64 la,
-						struct x86_emulate_ctxt *ctxt)
+						struct x86_emulate_ctxt *ctxt,
+						unsigned int flags)
 {
-	return !ctxt->ops->is_canonical_addr(ctxt, la);
+	return !ctxt->ops->is_canonical_addr(ctxt, la, flags);
 }
 
 /*
@@ -1733,7 +1734,8 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
 		if (ret != X86EMUL_CONTINUE)
 			return ret;
 		if (emul_is_noncanonical_address(get_desc_base(&seg_desc) |
-						 ((u64)base3 << 32), ctxt))
+						 ((u64)base3 << 32), ctxt,
+						 X86EMUL_F_DT_LOAD))
 			return emulate_gp(ctxt, err_code);
 	}
 
@@ -2516,8 +2518,8 @@ static int em_sysexit(struct x86_emulate_ctxt *ctxt)
 		ss_sel = cs_sel + 8;
 		cs.d = 0;
 		cs.l = 1;
-		if (emul_is_noncanonical_address(rcx, ctxt) ||
-		    emul_is_noncanonical_address(rdx, ctxt))
+		if (emul_is_noncanonical_address(rcx, ctxt, 0) ||
+		    emul_is_noncanonical_address(rdx, ctxt, 0))
 			return emulate_gp(ctxt, 0);
 		break;
 	}
@@ -3494,7 +3496,8 @@ static int em_lgdt_lidt(struct x86_emulate_ctxt *ctxt, bool lgdt)
 	if (rc != X86EMUL_CONTINUE)
 		return rc;
 	if (ctxt->mode == X86EMUL_MODE_PROT64 &&
-	    emul_is_noncanonical_address(desc_ptr.address, ctxt))
+	    emul_is_noncanonical_address(desc_ptr.address, ctxt,
+					 X86EMUL_F_DT_LOAD))
 		return emulate_gp(ctxt, 0);
 	if (lgdt)
 		ctxt->ops->set_gdt(ctxt, &desc_ptr);

arch/x86/kvm/kvm_emulate.h

@@ -94,6 +94,8 @@ struct x86_instruction_info {
 #define X86EMUL_F_FETCH			BIT(1)
 #define X86EMUL_F_IMPLICIT		BIT(2)
 #define X86EMUL_F_INVLPG		BIT(3)
+#define X86EMUL_F_MSR			BIT(4)
+#define X86EMUL_F_DT_LOAD		BIT(5)
 
 struct x86_emulate_ops {
 	void (*vm_bugged)(struct x86_emulate_ctxt *ctxt);
@@ -236,7 +238,8 @@ struct x86_emulate_ops {
 	gva_t (*get_untagged_addr)(struct x86_emulate_ctxt *ctxt, gva_t addr,
 				   unsigned int flags);
 
-	bool (*is_canonical_addr)(struct x86_emulate_ctxt *ctxt, gva_t addr);
+	bool (*is_canonical_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

@@ -8609,7 +8609,7 @@ static gva_t emulator_get_untagged_addr(struct x86_emulate_ctxt *ctxt,
 }
 
 static bool emulator_is_canonical_addr(struct x86_emulate_ctxt *ctxt,
-				       gva_t addr)
+				       gva_t addr, unsigned int flags)
 {
 	return !is_noncanonical_address(addr, emul_to_vcpu(ctxt));
 }