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From:   Vitaly Kuznetsov <vkuznets@redhat.com>
To:     Wanpeng Li <kernellwp@gmail.com>
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Subject: Re: [PATCH 1/2] KVM: X86: Filter the broadcast dest for IPI fastpath
In-Reply-To: <1585290240-18643-1-git-send-email-wanpengli@tencent.com>
References: <1585290240-18643-1-git-send-email-wanpengli@tencent.com>
Date:   Fri, 27 Mar 2020 10:00:14 +0100
Message-ID: <87h7ya41gh.fsf@vitty.brq.redhat.com>
MIME-Version: 1.0
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Sender: linux-kernel-owner@vger.kernel.org
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Wanpeng Li <kernellwp@gmail.com> writes:

> From: Wanpeng Li <wanpengli@tencent.com>
>
> Except destination shorthand, a destination value 0xffffffff is used to 
> broadcast interrupts, let's also filter this for single target IPI fastpath.
>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
>  arch/x86/kvm/lapic.c | 3 ---
>  arch/x86/kvm/lapic.h | 3 +++
>  arch/x86/kvm/x86.c   | 3 ++-
>  3 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index a38f1a8..88929b1 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -59,9 +59,6 @@
>  #define MAX_APIC_VECTOR			256
>  #define APIC_VECTORS_PER_REG		32
>  
> -#define APIC_BROADCAST			0xFF
> -#define X2APIC_BROADCAST		0xFFFFFFFFul
> -
>  static bool lapic_timer_advance_dynamic __read_mostly;
>  #define LAPIC_TIMER_ADVANCE_ADJUST_MIN	100	/* clock cycles */
>  #define LAPIC_TIMER_ADVANCE_ADJUST_MAX	10000	/* clock cycles */
> diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
> index bc76860..25b77a6 100644
> --- a/arch/x86/kvm/lapic.h
> +++ b/arch/x86/kvm/lapic.h
> @@ -17,6 +17,9 @@
>  #define APIC_BUS_CYCLE_NS       1
>  #define APIC_BUS_FREQUENCY      (1000000000ULL / APIC_BUS_CYCLE_NS)
>  
> +#define APIC_BROADCAST			0xFF
> +#define X2APIC_BROADCAST		0xFFFFFFFFul
> +
>  enum lapic_mode {
>  	LAPIC_MODE_DISABLED = 0,
>  	LAPIC_MODE_INVALID = X2APIC_ENABLE,
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index c4bb7d8..495709f 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1559,7 +1559,8 @@ static int handle_fastpath_set_x2apic_icr_irqoff(struct kvm_vcpu *vcpu, u64 data
>  
>  	if (((data & APIC_SHORT_MASK) == APIC_DEST_NOSHORT) &&
>  		((data & APIC_DEST_MASK) == APIC_DEST_PHYSICAL) &&
> -		((data & APIC_MODE_MASK) == APIC_DM_FIXED)) {
> +		((data & APIC_MODE_MASK) == APIC_DM_FIXED) &&
> +		((u32)(data >> 32) != X2APIC_BROADCAST)) {
>  
>  		data &= ~(1 << 12);
>  		kvm_apic_send_ipi(vcpu->arch.apic, (u32)data, (u32)(data >> 32));

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>

-- 
Vitaly