x86/S3: Restore CR4 earlier during resume

c/s 4304ff420e5 "x86/S3: Drop {save,restore}_rest_processor_state()
completely" moved CR4 restoration up into C, to account for the fact that MCE
was explicitly handled later.

However, time_resume() ends up making an EFI Runtime Service call, and EFI
explodes without OSFXSR, presumably when trying to spill %xmm registers onto
the stack.

Given this codepath, and the potential for other issues of a similar kind (TLB
flushing vs INVPCID, HVM logic vs VMXE, etc), restore CR4 in asm before
entering C.

Ignore the previous MCE special case, because its not actually necessary.  The
handler is already suitably configured from before suspend.

Fixes: 4304ff420e5 ("x86/S3: Drop {save,restore}_rest_processor_state() completely")
Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Tested-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>

diff --git a/xen/arch/x86/acpi/power.c b/xen/arch/x86/acpi/power.c
index 4fb1e7a1486fd33e719c91a369caf960b97b362a..7f162a4df9d78b2edce58ecbad80fbeeef060089 100644 (file)
--- a/xen/arch/x86/acpi/power.c
+++ b/xen/arch/x86/acpi/power.c
@@ -276,9 +276,6 @@ static int enter_state(u32 state)
 
     mcheck_init(&boot_cpu_data, false);
 
-    /* Restore CR4 from cached value, now MCE is set up. */
-    write_cr4(read_cr4());
-
     printk(XENLOG_INFO "Finishing wakeup from ACPI S%d state.\n", state);
 
     if ( (state == ACPI_STATE_S3) && error )

diff --git a/xen/arch/x86/acpi/wakeup_prot.S b/xen/arch/x86/acpi/wakeup_prot.S
index c6b3fcc93d934bb8134a77190858eed7d12c0d65..15052c300fa1b35b0d0728c6587f408b95ca37b2 100644 (file)
--- a/xen/arch/x86/acpi/wakeup_prot.S
+++ b/xen/arch/x86/acpi/wakeup_prot.S
@@ -1,3 +1,4 @@
+#include <asm/asm_defns.h>
 #include <asm/msr-index.h>
 #include <asm/page.h>
 #include <asm/processor.h>
@@ -110,6 +111,11 @@ ENTRY(s3_resume)
 
         call    load_system_tables
 
+        /* Restore CR4 from the cpuinfo block. */
+        GET_STACK_END(bx)
+        mov     STACK_CPUINFO_FIELD(cr4)(%rbx), %rax
+        mov     %rax, %cr4
+
 .Lsuspend_err:
         pop     %r15
         pop     %r14