| Message ID | 20190715171034.29709-1-andrew.cooper3@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | x86/suspend: Don't save/restore %cr8 | expand |
On 15.07.2019 19:10, Andrew Cooper wrote: > %cr8 is an alias of APIC_TASKPRI, which is handled by > lapic_{suspend,resume}() with the rest of the Local APIC state. Saving > and restoring the TPR state in isolation is not a clever idea. > > Drop it all. > > While editing wakeup_prot.S, trim its include list to just the headers > which are used, which is precicely none of them. > > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Acked-by: Jan Beulich <jbeulich@suse.com>
diff --git a/xen/arch/x86/acpi/wakeup_prot.S b/xen/arch/x86/acpi/wakeup_prot.S index 361751d290..4a92627436 100644 --- a/xen/arch/x86/acpi/wakeup_prot.S +++ b/xen/arch/x86/acpi/wakeup_prot.S @@ -1,13 +1,5 @@ .file __FILE__ .text - -#include <xen/multiboot.h> -#include <public/xen.h> -#include <asm/asm_defns.h> -#include <asm/desc.h> -#include <asm/page.h> -#include <asm/msr.h> - .code64 #define GREG(x) %r##x @@ -40,9 +32,6 @@ ENTRY(do_suspend_lowlevel) pushfq; popq SAVED_GREG(flags) - mov %cr8, GREG(ax) - mov GREG(ax), REF(saved_cr8) - mov %ss, REF(saved_ss) sgdt REF(saved_gdt) @@ -90,9 +79,6 @@ ENTRY(__ret_point) pushq %rax lretq 1: - mov REF(saved_cr8), %rax - mov %rax, %cr8 - pushq SAVED_GREG(flags) popfq @@ -149,4 +135,3 @@ saved_ldt: .quad 0,0 saved_cr0: .quad 0 saved_cr3: .quad 0 -saved_cr8: .quad 0
%cr8 is an alias of APIC_TASKPRI, which is handled by lapic_{suspend,resume}() with the rest of the Local APIC state. Saving and restoring the TPR state in isolation is not a clever idea. Drop it all. While editing wakeup_prot.S, trim its include list to just the headers which are used, which is precicely none of them. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> --- CC: Jan Beulich <JBeulich@suse.com> CC: Wei Liu <wl@xen.org> CC: Roger Pau Monné <roger.pau@citrix.com> CC: Juergen Gross <jgross@suse.com> This is a Xen mirror to my Linux patch of the same effect: https://lore.kernel.org/lkml/20190715151641.29210-1-andrew.cooper3@citrix.com/T/#u With a bit of care, I'm pretty sure the whole of wakeup_prot.S can disappear, but -ETIME right now. I've confirmed that after resume TPR retains its value of 0x10. However, all attempts to debug the internals of lapic_suspend/resume have eluded me, including manually poking the UART. Again, -ETIME to investigate further. --- xen/arch/x86/acpi/wakeup_prot.S | 15 --------------- 1 file changed, 15 deletions(-)