From baf055ec2180fc22ab38877990bda7a5e26654a5 Mon Sep 17 00:00:00 2001
From: Kaige Fu <kaige.fu@intel.com>
Date: Tue, 31 Jul 2018 14:19:58 +0800
Subject: [PATCH] HV: instr_emul: Using size2mask array directly

There are size2mask array to convert addsize to corresponding mask and function
vie_size2mask doing the same thing except validation check of addrsize.
Theoretically, addrsize can only be one of (1, 2, 4, 8). So, the check of addrsize
is unnecessary.

This patch remove vie_size2mask and use size2maks directly.

Signed-off-by: Kaige Fu <kaige.fu@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>
---
 hypervisor/arch/x86/guest/instr_emul.c | 30 ++++++++++----------------
 hypervisor/arch/x86/guest/instr_emul.h |  2 --
 2 files changed, 11 insertions(+), 21 deletions(-)

diff --git a/hypervisor/arch/x86/guest/instr_emul.c b/hypervisor/arch/x86/guest/instr_emul.c
index 4e6faa832..8ca7ec575 100644
--- a/hypervisor/arch/x86/guest/instr_emul.c
+++ b/hypervisor/arch/x86/guest/instr_emul.c
@@ -215,10 +215,10 @@ static const struct instr_emul_vie_op one_byte_opcodes[256] = {
 #define	GB				(1024 * 1024 * 1024)
 
 static uint64_t size2mask[9] = {
-	[1] = 0xffUL,
-	[2] = 0xffffUL,
-	[4] = 0xffffffffUL,
-	[8] = 0xffffffffffffffffUL,
+	[1] = (1UL << 8U) - 1UL,
+	[2] = (1UL << 16U) - 1UL,
+	[4] = (1UL << 32U) - 1UL,
+	[8] = ~0UL,
 };
 
 static void
@@ -694,7 +694,7 @@ emulate_movs(struct vcpu *vcpu, __unused uint64_t gpa, struct instr_emul_vie *vi
 		 * The count register is %rcx, %ecx or %cx depending on the
 		 * address size of the instruction.
 		 */
-		if ((rcx & vie_size2mask(vie->addrsize)) == 0UL) {
+		if ((rcx & size2mask[vie->addrsize]) == 0UL) {
 			error = 0;
 			goto done;
 		}
@@ -742,7 +742,7 @@ emulate_movs(struct vcpu *vcpu, __unused uint64_t gpa, struct instr_emul_vie *vi
 		/*
 		 * Repeat the instruction if the count register is not zero.
 		 */
-		if ((rcx & vie_size2mask(vie->addrsize)) != 0UL) {
+		if ((rcx & size2mask[vie->addrsize]) != 0UL) {
 			vcpu_retain_rip(vcpu);
 		}
 	}
@@ -772,7 +772,7 @@ emulate_stos(struct vcpu *vcpu, uint64_t gpa, struct instr_emul_vie *vie,
 		 * The count register is %rcx, %ecx or %cx depending on the
 		 * address size of the instruction.
 		 */
-		if ((rcx & vie_size2mask(vie->addrsize)) == 0UL) {
+		if ((rcx & size2mask[vie->addrsize]) == 0UL) {
 			return 0;
 		}
 	}
@@ -804,7 +804,7 @@ emulate_stos(struct vcpu *vcpu, uint64_t gpa, struct instr_emul_vie *vie,
 		/*
 		 * Repeat the instruction if the count register is not zero.
 		 */
-		if ((rcx & vie_size2mask(vie->addrsize)) != 0UL) {
+		if ((rcx & size2mask[vie->addrsize]) != 0UL) {
 			vcpu_retain_rip(vcpu);
 		}
 	}
@@ -1549,14 +1549,6 @@ vie_canonical_check(enum vm_cpu_mode cpu_mode, uint64_t gla)
 	}
 }
 
-uint64_t
-vie_size2mask(uint8_t size)
-{
-	ASSERT(size == 1U || size == 2U || size == 4U || size == 8U,
-			"vie_size2mask: invalid size %hhu", size);
-	return size2mask[size];
-}
-
 int
 vie_calculate_gla(enum vm_cpu_mode cpu_mode, enum cpu_reg_name seg,
 	struct seg_desc *desc, uint64_t offset_arg, uint8_t length_arg,
@@ -1649,7 +1641,7 @@ vie_calculate_gla(enum vm_cpu_mode cpu_mode, enum cpu_reg_name seg,
 		}
 
 		while (length > 0U) {
-			offset &= vie_size2mask(addrsize);
+			offset &= size2mask[addrsize];
 			if (offset < low_limit || offset > high_limit) {
 				return -1;
 			}
@@ -1673,8 +1665,8 @@ vie_calculate_gla(enum vm_cpu_mode cpu_mode, enum cpu_reg_name seg,
 	 * Truncate 'firstoff' to the effective address size before adding
 	 * it to the segment base.
 	 */
-	firstoff &= vie_size2mask(addrsize);
-	*gla = (segbase + firstoff) & vie_size2mask(glasize);
+	firstoff &= size2mask[addrsize];
+	*gla = (segbase + firstoff) & size2mask[glasize];
 	return 0;
 }
 
diff --git a/hypervisor/arch/x86/guest/instr_emul.h b/hypervisor/arch/x86/guest/instr_emul.h
index 527e88ebf..5dd4f8c88 100644
--- a/hypervisor/arch/x86/guest/instr_emul.h
+++ b/hypervisor/arch/x86/guest/instr_emul.h
@@ -68,8 +68,6 @@ int vie_alignment_check(uint8_t cpl, uint8_t operand_size, uint64_t cr0,
 /* Returns 1 if the 'gla' is not canonical and 0 otherwise. */
 int vie_canonical_check(enum vm_cpu_mode cpu_mode, uint64_t gla);
 
-uint64_t vie_size2mask(uint8_t size);
-
 int vie_calculate_gla(enum vm_cpu_mode cpu_mode, enum cpu_reg_name seg,
 	struct seg_desc *desc, uint64_t offset_arg, uint8_t length_arg,
 	uint8_t addrsize, uint32_t prot, uint64_t *gla);