x86/S3: Restore CR4 earlier during resume
authorAndrew Cooper <andrew.cooper3@citrix.com>
Fri, 2 Oct 2020 17:49:32 +0000 (18:49 +0100)
committerAndrew Cooper <andrew.cooper3@citrix.com>
Tue, 6 Oct 2020 11:28:37 +0000 (12:28 +0100)
commit7f66c0dc41ae5f770c614e516810eb1f336e2470
tree4b77470846411dbaae6003cd1c9b72f134ab9bb8
parent30bfa535fa9de47c47d0655e502eaf23724f837b
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>
xen/arch/x86/acpi/power.c
xen/arch/x86/acpi/wakeup_prot.S