lkml.org 
[lkml]   [2019]   [Jul]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] KVM: x86: init x2apic_enabled() once
From
Date


On 07/23/2019 06:06 AM, luferry@163.com wrote:
> From: luferry <luferry@163.com>
>
> x2apic_eanbled() costs about 200 cycles
> when guest trigger halt pretty high, pi ops in hotpath
>
> Signed-off-by: luferry <luferry@163.com>
> ---
> 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@oracle.com>

\
 
 \ /
  Last update: 2019-07-23 23:29    [W:0.053 / U:1.088 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site