[PATCH 1/3] x86/S3: Use percpu_traps_init() rather than opencoding SYSCALL/SYSENTER restoration

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

This make the S3 BSP path consistent with AP paths, and reduces the amount of
state needing stashing specially.  Also, it takes care of re-setting up Xen's
LBR configuration if requested, which was missing previously.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/acpi/suspend.c | 25 ++-----------------------
 1 file changed, 2 insertions(+), 23 deletions(-)

diff --git a/xen/arch/x86/acpi/suspend.c b/xen/arch/x86/acpi/suspend.c
index 32d0f71ffd..1c2f1c470e 100644
--- a/xen/arch/x86/acpi/suspend.c
+++ b/xen/arch/x86/acpi/suspend.c
@@ -15,8 +15,6 @@
 #include <asm/xstate.h>
 #include <xen/hypercall.h>
 
-static unsigned long saved_lstar, saved_cstar;
-static unsigned long saved_sysenter_esp, saved_sysenter_eip;
 static unsigned long saved_fs_base, saved_gs_base, saved_kernel_gs_base;
 static uint64_t saved_xcr0;
 
@@ -25,14 +23,6 @@ void save_rest_processor_state(void)
     saved_fs_base = rdfsbase();
     saved_gs_base = rdgsbase();
     rdmsrl(MSR_SHADOW_GS_BASE, saved_kernel_gs_base);
-    rdmsrl(MSR_CSTAR, saved_cstar);
-    rdmsrl(MSR_LSTAR, saved_lstar);
-
-    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();
@@ -46,24 +36,13 @@ void restore_rest_processor_state(void)
     /* Restore full CR4 (inc MCE) now that the IDT is in place. */
     write_cr4(mmu_cr4_features);
 
-    /* Recover syscall MSRs */
-    wrmsrl(MSR_LSTAR, saved_lstar);
-    wrmsrl(MSR_CSTAR, saved_cstar);
-    wrmsrl(MSR_STAR, XEN_MSR_STAR);
-    wrmsrl(MSR_SYSCALL_MASK, XEN_SYSCALL_MASK);
+    /* (re)initialise SYSCALL/SYSENTER state, amongst other things. */
+    percpu_traps_init();
 
     wrfsbase(saved_fs_base);
     wrgsbase(saved_gs_base);
     wrmsrl(MSR_SHADOW_GS_BASE, saved_kernel_gs_base);
 
-    if ( cpu_has_sep )
-    {
-        /* Recover sysenter MSRs */
-        wrmsrl(MSR_IA32_SYSENTER_ESP, saved_sysenter_esp);
-        wrmsrl(MSR_IA32_SYSENTER_EIP, saved_sysenter_eip);
-        wrmsr(MSR_IA32_SYSENTER_CS, __HYPERVISOR_CS, 0);
-    }
-
     if ( cpu_has_xsave && !set_xcr0(saved_xcr0) )
         BUG();
 
-- 
2.11.0