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local_gva2gpa_common: optimize code

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Remove unreachable code branch in line 163:
if CR0 enabled WP, supervisor-mode writing a read-only page have
been checked in line 109.

Merge redundant checking:
if smap is enabled, supervisor-mode can't access user-mode address
when eflags.ac disabled.

Tracked-On: 
Signed-off-by: Haoyu Tang <haoyu.tang@intel.com>
This commit is contained in:
Haoyu Tang 2024-08-27 13:54:04 +08:00 committed by acrnsi-robot
parent 0198edf145
commit fa1f2ba7df
1 changed files with 2 additions and 30 deletions

32
hypervisor/arch/x86/guest/guest_memory.c
View File

@ -65,7 +65,6 @@ static int32_t local_gva2gpa_common(struct acrn_vcpu *vcpu, const struct page_wa
int32_t ret = 0;
int32_t fault = 0;
bool is_user_mode_addr = true;
bool is_page_rw_flags_on = true;
if (pw_info->level < 1U) {
ret = -EINVAL;
@ -108,7 +107,6 @@ static int32_t local_gva2gpa_common(struct acrn_vcpu *vcpu, const struct page_wa
* Case2: Usermode */
fault = 1;
}
is_page_rw_flags_on = false;
}
}
@ -142,34 +140,8 @@ static int32_t local_gva2gpa_common(struct acrn_vcpu *vcpu, const struct page_wa
*/
/* if smap is enabled and supervisor-mode access */
if ((fault == 0) && pw_info->is_smap_on && (!pw_info->is_user_mode_access) &&
is_user_mode_addr) {
bool acflag = ((vcpu_get_rflags(vcpu) & RFLAGS_AC) != 0UL);
/* read from user mode address, eflags.ac = 0 */
if ((!pw_info->is_write_access) && (!acflag)) {
fault = 1;
} else if (pw_info->is_write_access) {
/* write to user mode address */
/* cr0.wp = 0, eflags.ac = 0 */
if ((!pw_info->wp) && (!acflag)) {
fault = 1;
}
/* cr0.wp = 1, eflags.ac = 1, r/w flag is 0
* on any paging structure entry
*/
if (pw_info->wp && acflag && (!is_page_rw_flags_on)) {
fault = 1;
}
/* cr0.wp = 1, eflags.ac = 0 */
if (pw_info->wp && (!acflag)) {
fault = 1;
}
} else {
/* do nothing */
}
is_user_mode_addr && ((vcpu_get_rflags(vcpu) & RFLAGS_AC) == 0UL)) {
fault = 1;
}
/* instruction fetch from user-mode address, smep on */