Commit 440b2a7a authored Aug 04, 2022 by Paolo Bonzini Committed by Zheng Zengkai Aug 04, 2022

KVM: x86: Do not change ICR on write to APIC_SELF_IPI

stable inclusion
from stable-v5.10.115
commit a474ee5ececc19c764c718c76550c5650e54a3be
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5IZ9C

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a474ee5ececc19c764c718c76550c5650e54a3be



--------------------------------

[ Upstream commit d22a81b3 ]

Emulating writes to SELF_IPI with a write to ICR has an unwanted side effect:
the value of ICR in vAPIC page gets changed.  The lists SELF_IPI as write-only,
with no associated MMIO offset, so any write should have no visible side
effect in the vAPIC page.

Reported-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>

parent b5f6c150

arch/x86/kvm/lapic.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -2111,10 +2111,9 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
		break;

		case APIC_SELF_IPI:
		if (apic_x2apic_mode(apic)) {
		kvm_lapic_reg_write(apic, APIC_ICR,
		APIC_DEST_SELF \| (val & APIC_VECTOR_MASK));
		} else
		if (apic_x2apic_mode(apic))
		kvm_apic_send_ipi(apic, APIC_DEST_SELF \| (val & APIC_VECTOR_MASK), 0);
		else
		ret = 1;
		break;
		default: