On 07/23/2019 06:06 AM, luferry@xxxxxxx wrote:
From: luferry <luferry@xxxxxxx>
x2apic_eanbled() costs about 200 cycles
when guest trigger halt pretty high, pi ops in hotpath
Signed-off-by: luferry <luferry@xxxxxxx>
---
arch/x86/kvm/vmx/vmx.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d98eac371c0a..e17dbf011e47 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -186,6 +186,8 @@ static DEFINE_STATIC_KEY_FALSE(vmx_l1d_should_flush);
static DEFINE_STATIC_KEY_FALSE(vmx_l1d_flush_cond);
static DEFINE_MUTEX(vmx_l1d_flush_mutex);
+static int __read_mostly host_x2apic_enabled;
+
/* Storage for pre module init parameter parsing */
static enum vmx_l1d_flush_state __read_mostly vmentry_l1d_flush_param = VMENTER_L1D_FLUSH_AUTO;
@@ -1204,7 +1206,7 @@ static void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)
dest = cpu_physical_id(cpu);
- if (x2apic_enabled())
+ if (host_x2apic_enabled)
new.ndst = dest;
else
new.ndst = (dest << 8) & 0xFF00;
@@ -7151,7 +7153,7 @@ static void __pi_post_block(struct kvm_vcpu *vcpu)
dest = cpu_physical_id(vcpu->cpu);
- if (x2apic_enabled())
+ if (host_x2apic_enabled)
new.ndst = dest;
else
new.ndst = (dest << 8) & 0xFF00;
@@ -7221,7 +7223,7 @@ static int pi_pre_block(struct kvm_vcpu *vcpu)
*/
dest = cpu_physical_id(vcpu->pre_pcpu);
- if (x2apic_enabled())
+ if (host_x2apic_enabled)
new.ndst = dest;
else
new.ndst = (dest << 8) & 0xFF00;
@@ -7804,6 +7806,8 @@ static int __init vmx_init(void)
}
#endif
+ host_x2apic_enabled = x2apic_enabled();
+
r = kvm_init(&vmx_x86_ops, sizeof(struct vcpu_vmx),
__alignof__(struct vcpu_vmx), THIS_MODULE);
if (r)
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
