Jan Beulich
2012-Sep-11 11:53 UTC
[PATCH] x86: use only a single branch for upcall-pending exit path checks
This utilizes the fact that the two bytes of interest are adjacent to
one another and that the resulting 16-bit values of interest are within
a contiguous range of numbers.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/arch/x86/x86_32/entry.S
+++ b/xen/arch/x86/x86_32/entry.S
@@ -219,10 +219,10 @@ test_all_events:
jnz process_nmi
test_guest_events:
movl VCPU_vcpu_info(%ebx),%eax
- testb $0xFF,VCPUINFO_upcall_mask(%eax)
- jnz restore_all_guest
- testb $0xFF,VCPUINFO_upcall_pending(%eax)
- jz restore_all_guest
+ movzwl VCPUINFO_upcall_pending(%eax),%eax
+ decl %eax
+ cmpl $0xfe,%eax
+ ja restore_all_guest
/*process_guest_events:*/
sti
leal VCPU_trap_bounce(%ebx),%edx
--- a/xen/arch/x86/x86_64/compat/entry.S
+++ b/xen/arch/x86/x86_64/compat/entry.S
@@ -108,10 +108,10 @@ ENTRY(compat_test_all_events)
jnz compat_process_nmi
compat_test_guest_events:
movq VCPU_vcpu_info(%rbx),%rax
- testb $0xFF,COMPAT_VCPUINFO_upcall_mask(%rax)
- jnz compat_restore_all_guest
- testb $0xFF,COMPAT_VCPUINFO_upcall_pending(%rax)
- jz compat_restore_all_guest
+ movzwl COMPAT_VCPUINFO_upcall_pending(%rax),%eax
+ decl %eax
+ cmpl $0xfe,%eax
+ ja compat_restore_all_guest
/*compat_process_guest_events:*/
sti
leaq VCPU_trap_bounce(%rbx),%rdx
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -199,8 +199,8 @@ test_all_events:
movl VCPU_processor(%rbx),%eax
shl $IRQSTAT_shift,%rax
leaq irq_stat(%rip),%rcx
- testl $~0,(%rcx,%rax,1)
- jnz process_softirqs
+ cmpl $0,(%rcx,%rax,1)
+ jne process_softirqs
testb $1,VCPU_mce_pending(%rbx)
jnz process_mce
.Ltest_guest_nmi:
@@ -208,10 +208,10 @@ test_all_events:
jnz process_nmi
test_guest_events:
movq VCPU_vcpu_info(%rbx),%rax
- testb $0xFF,VCPUINFO_upcall_mask(%rax)
- jnz restore_all_guest
- testb $0xFF,VCPUINFO_upcall_pending(%rax)
- jz restore_all_guest
+ movzwl VCPUINFO_upcall_pending(%rax),%eax
+ decl %eax
+ cmpl $0xfe,%eax
+ ja restore_all_guest
/*process_guest_events:*/
sti
leaq VCPU_trap_bounce(%rbx),%rdx
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Keir Fraser
2012-Sep-11 13:33 UTC
Re: [PATCH] x86: use only a single branch for upcall-pending exit path checks
On 11/09/2012 12:53, "Jan Beulich" <JBeulich@suse.com> wrote:> This utilizes the fact that the two bytes of interest are adjacent to > one another and that the resulting 16-bit values of interest are within > a contiguous range of numbers. > > Signed-off-by: Jan Beulich <jbeulich@suse.com>Acked-by: Keir Fraser <keir@xen.org>> --- a/xen/arch/x86/x86_32/entry.S > +++ b/xen/arch/x86/x86_32/entry.S > @@ -219,10 +219,10 @@ test_all_events: > jnz process_nmi > test_guest_events: > movl VCPU_vcpu_info(%ebx),%eax > - testb $0xFF,VCPUINFO_upcall_mask(%eax) > - jnz restore_all_guest > - testb $0xFF,VCPUINFO_upcall_pending(%eax) > - jz restore_all_guest > + movzwl VCPUINFO_upcall_pending(%eax),%eax > + decl %eax > + cmpl $0xfe,%eax > + ja restore_all_guest > /*process_guest_events:*/ > sti > leal VCPU_trap_bounce(%ebx),%edx > --- a/xen/arch/x86/x86_64/compat/entry.S > +++ b/xen/arch/x86/x86_64/compat/entry.S > @@ -108,10 +108,10 @@ ENTRY(compat_test_all_events) > jnz compat_process_nmi > compat_test_guest_events: > movq VCPU_vcpu_info(%rbx),%rax > - testb $0xFF,COMPAT_VCPUINFO_upcall_mask(%rax) > - jnz compat_restore_all_guest > - testb $0xFF,COMPAT_VCPUINFO_upcall_pending(%rax) > - jz compat_restore_all_guest > + movzwl COMPAT_VCPUINFO_upcall_pending(%rax),%eax > + decl %eax > + cmpl $0xfe,%eax > + ja compat_restore_all_guest > /*compat_process_guest_events:*/ > sti > leaq VCPU_trap_bounce(%rbx),%rdx > --- a/xen/arch/x86/x86_64/entry.S > +++ b/xen/arch/x86/x86_64/entry.S > @@ -199,8 +199,8 @@ test_all_events: > movl VCPU_processor(%rbx),%eax > shl $IRQSTAT_shift,%rax > leaq irq_stat(%rip),%rcx > - testl $~0,(%rcx,%rax,1) > - jnz process_softirqs > + cmpl $0,(%rcx,%rax,1) > + jne process_softirqs > testb $1,VCPU_mce_pending(%rbx) > jnz process_mce > .Ltest_guest_nmi: > @@ -208,10 +208,10 @@ test_all_events: > jnz process_nmi > test_guest_events: > movq VCPU_vcpu_info(%rbx),%rax > - testb $0xFF,VCPUINFO_upcall_mask(%rax) > - jnz restore_all_guest > - testb $0xFF,VCPUINFO_upcall_pending(%rax) > - jz restore_all_guest > + movzwl VCPUINFO_upcall_pending(%rax),%eax > + decl %eax > + cmpl $0xfe,%eax > + ja restore_all_guest > /*process_guest_events:*/ > sti > leaq VCPU_trap_bounce(%rbx),%rdx > > > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xen.org > http://lists.xen.org/xen-devel