[Xen-devel] [PATCH] x86/cpu: Use cpu_has_sep for configuring the SYSENTER MSRs

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Currently, configuration of the SYSENTER MSRs are behind a vendor check for
Intel and Centaur, but this misses Zhaoxin.

Use the feature bit, rather than a vendor check.  cpu_has_sep is cleared early
for AMD processors, which can't use SYSENTER/SYSEXIT when operating in long
mode.

Suggested-by: Jan Beulich <JBeulich@xxxxxxxx>
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: FionaLi-oc <fionali-oc@xxxxxxxxxxx>

Please double check that this works for Zhaoxin.  I've tried Intel and AMD.
---
 xen/arch/x86/acpi/suspend.c | 6 ++++--
 xen/arch/x86/x86_64/traps.c | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/acpi/suspend.c b/xen/arch/x86/acpi/suspend.c
index 9e69bf2..ba9d2e1 100644
--- a/xen/arch/x86/acpi/suspend.c
+++ b/xen/arch/x86/acpi/suspend.c
@@ -27,11 +27,13 @@ void save_rest_processor_state(void)
     rdmsrl(MSR_SHADOW_GS_BASE, saved_kernel_gs_base);
     rdmsrl(MSR_CSTAR, saved_cstar);
     rdmsrl(MSR_LSTAR, saved_lstar);
-    if ( boot_cpu_data.x86_vendor & (X86_VENDOR_INTEL | X86_VENDOR_CENTAUR) )
+
+    if ( cpu_has_sep )
     {
         rdmsrl(MSR_IA32_SYSENTER_ESP, saved_sysenter_esp);
         rdmsrl(MSR_IA32_SYSENTER_EIP, saved_sysenter_eip);
     }
+
     if ( cpu_has_xsave )
         saved_xcr0 = get_xcr0();
 }
@@ -51,7 +53,7 @@ void restore_rest_processor_state(void)
     wrgsbase(saved_gs_base);
     wrmsrl(MSR_SHADOW_GS_BASE, saved_kernel_gs_base);
 
-    if ( boot_cpu_data.x86_vendor & (X86_VENDOR_INTEL | X86_VENDOR_CENTAUR) )
+    if ( cpu_has_sep )
     {
         /* Recover sysenter MSRs */
         wrmsrl(MSR_IA32_SYSENTER_ESP, saved_sysenter_esp);
diff --git a/xen/arch/x86/x86_64/traps.c b/xen/arch/x86/x86_64/traps.c
index 44af765..cb4bf0a 100644
--- a/xen/arch/x86/x86_64/traps.c
+++ b/xen/arch/x86/x86_64/traps.c
@@ -334,7 +334,7 @@ void subarch_percpu_traps_init(void)
                                    (unsigned long)lstar_enter);
     stub_va += offset;
 
-    if ( boot_cpu_data.x86_vendor & (X86_VENDOR_INTEL | X86_VENDOR_CENTAUR) )
+    if ( cpu_has_sep )
     {
         /* SYSENTER entry. */
         wrmsrl(MSR_IA32_SYSENTER_ESP, stack_bottom);
-- 
2.1.4


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