The STI instances were moved (or added in the INT80 case) to meet TLB
flush requirements. When XPTI is disabled, they can be put back where
they were (or omitted in the INT80 case).
Signed-off-by: Jan Beulich
---
v4: Split off from earlier patch.
---
TBD: It is questionable whether having two back-to-back alternatives
keyed to the same feature is a good idea. The original patch had
them as a single instance each, but the variant here requires fewer
(explicit) labels and hence results in overall more readable code.
--- a/xen/arch/x86/x86_64/compat/entry.S
+++ b/xen/arch/x86/x86_64/compat/entry.S
@@ -194,7 +194,7 @@ ENTRY(compat_post_handle_exception)
/* See lstar_enter for entry register state. */
ENTRY(cstar_enter)
-/* sti could live here when we don't switch page tables below. */
+ALTERNATIVE nop, sti, X86_FEATURE_NO_XPTI
CR4_PV32_RESTORE
movq 8(%rsp),%rax /* Restore %rax. */
movq $FLAT_KERNEL_SS,8(%rsp)
@@ -220,7 +220,7 @@ ENTRY(cstar_enter)
mov %r12, STACK_CPUINFO_FIELD(xen_cr3)(%rbx)
.Lcstar_cr3_okay:
ALTERNATIVE_NOP .Lcstar_cr3_start, .Lcstar_cr3_okay,
X86_FEATURE_NO_XPTI
-sti
+ALTERNATIVE sti, "", X86_FEATURE_NO_XPTI
movq STACK_CPUINFO_FIELD(current_vcpu)(%rbx), %rbx
movq VCPU_domain(%rbx),%rcx
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -245,7 +245,7 @@ UNLIKELY_END(exit_cr3)
* %ss must be saved into the space left by the trampoline.
*/
ENTRY(lstar_enter)
-/* sti could live here when we don't switch page tables below. */
+ALTERNATIVE nop, sti, X86_FEATURE_NO_XPTI
movq 8(%rsp),%rax /* Restore %rax. */
movq $FLAT_KERNEL_SS,8(%rsp)
pushq %r11
@@ -270,7 +270,7 @@ ENTRY(lstar_enter)
mov %r12, STACK_CPUINFO_FIELD(xen_cr3)(%rbx)
.Llstar_cr3_okay:
ALTERNATIVE_NOP .Llstar_cr3_start, .Llstar_cr3_okay,
X86_FEATURE_NO_XPTI
-sti
+ALTERNATIVE sti, "", X86_FEATURE_NO_XPTI
movq STACK_CPUINFO_FIELD(current_vcpu)(%rbx), %rbx
testb $TF_kernel_mode,VCPU_thread_flags(%rbx)
@@ -281,7 +281,7 @@ ENTRY(lstar_enter)
jmp test_all_events
ENTRY(sysenter_entry)
-/* sti could live here when we don't switch page tables below. */
+ALTERNATIVE nop, sti, X86_FEATURE_NO_XPTI
pushq $FLAT_USER_SS
pushq $0
pushfq
@@ -310,7 +310,7 @@ GLOBAL(sysenter_eflags_saved)
mov %r12, STACK_CPUINFO_FIELD(xen_cr3)(%rbx)
.Lsyse_cr3_okay:
ALTERNATIVE_NOP .Lsyse_cr3_start, .Lsyse_cr3_okay, X86_FEATURE_NO_XPTI
-sti
+ALTERNATIVE sti, "", X86_FEATURE_NO_XPTI
movq STACK_CPUINFO_FIELD(current_vcpu)(%rbx), %rbx
cmpb $0,VCPU_sysenter_disables_events(%rbx)
@@ -363,7 +363,7 @@ ENTRY(int80_direct_trap)
mov %r12, STACK_CPUINFO_FIELD(xen_cr3)(%rbx)
.Lint80_cr3_okay:
ALTERNATIVE_NOP .Lint80_cr3_start, .Lint80_cr3_okay,
X86_FEATURE_NO_XPTI
-sti
+ALTERNATIVE sti, "", X86_FEATURE_NO_XPTI
cmpb $0,untrusted_msi(%rip)
UNLIKELY_START(ne, msi_check)
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