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| author | Michael S. Tsirkin <mst@redhat.com> | 2012-06-24 20:25:07 +0400 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2012-06-25 13:40:55 +0400 |
| commit | ae7a2a3fb6f8b784c2752863f4f1f20c656f76fb (patch) | |
| tree | 5f4053265d244bb12ccff88494d70124b6d603c3 /arch/x86/kvm/cpuid.c | |
| parent | d905c0693514e6f713b207377b67c9972c5d7d49 (diff) | |
| download | linux-ae7a2a3fb6f8b784c2752863f4f1f20c656f76fb.tar.xz | |
KVM: host side for eoi optimization
Implementation of PV EOI using shared memory.
This reduces the number of exits an interrupt
causes as much as by half.
The idea is simple: there's a bit, per APIC, in guest memory,
that tells the guest that it does not need EOI.
We set it before injecting an interrupt and clear
before injecting a nested one. Guest tests it using
a test and clear operation - this is necessary
so that host can detect interrupt nesting -
and if set, it can skip the EOI MSR.
There's a new MSR to set the address of said register
in guest memory. Otherwise not much changed:
- Guest EOI is not required
- Register is tested & ISR is automatically cleared on exit
For testing results see description of previous patch
'kvm_para: guest side for eoi avoidance'.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86/kvm/cpuid.c')
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 7df1c6d839fb..61ccbdf3d0ac 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -409,6 +409,7 @@ static int do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, (1 << KVM_FEATURE_NOP_IO_DELAY) | (1 << KVM_FEATURE_CLOCKSOURCE2) | (1 << KVM_FEATURE_ASYNC_PF) | + (1 << KVM_FEATURE_PV_EOI) | (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT); if (sched_info_on()) |