linux-kernel - [PATCH 1/2] KVM: X86: Filter the broadcast dest for IPI fastpath

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Date:   Fri, 27 Mar 2020 14:23:59 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>
Subject: [PATCH 1/2] KVM: X86: Filter the broadcast dest for IPI fastpath

From: Wanpeng Li <wanpengli@...cent.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@...cent.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));
-- 
2.7.4