[PATCH v9 1/6] KVM: x86: Consolidate flags for __linearize()

[Binbin Wu]

Consolidate two bool parameters (write/fetch) of __linearize() into a
'u32 flags' parameter to make the function be more concise and future
extendable, i.e. to support Intel Linear Address Masking (LAM), which
allows high non-address bits of linear address to be used as metadata.

Define two flags to replace the two bools.  A new flag will be added to
to support LAM to skip masking off metadata bits of linear address
under some conditions.

No functional change intended.

Signed-off-by: Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx>
Reviewed-by: Chao Gao <chao.gao@xxxxxxxxx>
Acked-by: Kai Huang <kai.huang@xxxxxxxxx>
---
 arch/x86/kvm/emulate.c     | 19 ++++++++++---------
 arch/x86/kvm/kvm_emulate.h |  4 ++++
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 936a397a08cd..e89afc39e56f 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -687,8 +687,8 @@ static unsigned insn_alignment(struct x86_emulate_ctxt *ctxt, unsigned size)
 static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
 				       struct segmented_address addr,
 				       unsigned *max_size, unsigned size,
-				       bool write, bool fetch,
-				       enum x86emul_mode mode, ulong *linear)
+				       enum x86emul_mode mode, ulong *linear,
+				       u32 flags)
 {
 	struct desc_struct desc;
 	bool usable;
@@ -718,10 +718,10 @@ static __always_inline int __linearize(struct x86_emulate_ctxt *ctxt,
 			goto bad;
 		/* code segment in protected mode or read-only data segment */
 		if ((((ctxt->mode != X86EMUL_MODE_REAL) && (desc.type & 8))
-					|| !(desc.type & 2)) && write)
+			|| !(desc.type & 2)) && (flags & X86EMUL_F_WRITE))
 			goto bad;
 		/* unreadable code segment */
-		if (!fetch && (desc.type & 8) && !(desc.type & 2))
+		if (!(flags & X86EMUL_F_FETCH) && (desc.type & 8) && !(desc.type & 2))
 			goto bad;
 		lim = desc_limit_scaled(&desc);
 		if (!(desc.type & 8) && (desc.type & 4)) {
@@ -757,8 +757,8 @@ static int linearize(struct x86_emulate_ctxt *ctxt,
 		     ulong *linear)
 {
 	unsigned max_size;
-	return __linearize(ctxt, addr, &max_size, size, write, false,
-			   ctxt->mode, linear);
+	return __linearize(ctxt, addr, &max_size, size, ctxt->mode, linear,
+			   write ? X86EMUL_F_WRITE : 0);
 }
 
 static inline int assign_eip(struct x86_emulate_ctxt *ctxt, ulong dst)
@@ -771,7 +771,8 @@ static inline int assign_eip(struct x86_emulate_ctxt *ctxt, ulong dst)
 
 	if (ctxt->op_bytes != sizeof(unsigned long))
 		addr.ea = dst & ((1UL << (ctxt->op_bytes << 3)) - 1);
-	rc = __linearize(ctxt, addr, &max_size, 1, false, true, ctxt->mode, &linear);
+	rc = __linearize(ctxt, addr, &max_size, 1, ctxt->mode, &linear,
+			 X86EMUL_F_FETCH);
 	if (rc == X86EMUL_CONTINUE)
 		ctxt->_eip = addr.ea;
 	return rc;
@@ -907,8 +908,8 @@ static int __do_insn_fetch_bytes(struct x86_emulate_ctxt *ctxt, int op_size)
 	 * boundary check itself.  Instead, we use max_size to check
 	 * against op_size.
 	 */
-	rc = __linearize(ctxt, addr, &max_size, 0, false, true, ctxt->mode,
-			 &linear);
+	rc = __linearize(ctxt, addr, &max_size, 0, ctxt->mode, &linear,
+			 X86EMUL_F_FETCH);
 	if (unlikely(rc != X86EMUL_CONTINUE))
 		return rc;
 
diff --git a/arch/x86/kvm/kvm_emulate.h b/arch/x86/kvm/kvm_emulate.h
index ab65f3a47dfd..5b9ec610b2cb 100644
--- a/arch/x86/kvm/kvm_emulate.h
+++ b/arch/x86/kvm/kvm_emulate.h
@@ -88,6 +88,10 @@ struct x86_instruction_info {
 #define X86EMUL_IO_NEEDED       5 /* IO is needed to complete emulation */
 #define X86EMUL_INTERCEPTED     6 /* Intercepted by nested VMCB/VMCS */
 
+/* x86-specific emulation flags */
+#define X86EMUL_F_FETCH			BIT(0)
+#define X86EMUL_F_WRITE			BIT(1)
+
 struct x86_emulate_ops {
 	void (*vm_bugged)(struct x86_emulate_ctxt *ctxt);
 	/*
-- 
2.25.1