All of lore.kernel.org
 help / color / mirror / Atom feed
From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Wanpeng Li" <wanpeng.li@hotmail.com>
Subject: [PATCH] KVM: X86: Fix loss of pending INIT due to race
Date: Sun, 30 Jul 2017 02:42:57 -0700	[thread overview]
Message-ID: <1501407777-2504-1-git-send-email-wanpeng.li@hotmail.com> (raw)

From: Wanpeng Li <wanpeng.li@hotmail.com>

When SMP VM start, AP may lost INIT because of receiving INIT between
kvm_vcpu_ioctl_x86_get/set_vcpu_events.

       vcpu 0                             vcpu 1
                                   kvm_vcpu_ioctl_x86_get_vcpu_events
                                     events->smi.latched_init = 0
  send INIT to vcpu1
    set vcpu1's pending_events
                                   kvm_vcpu_ioctl_x86_set_vcpu_events
                                      if (events->smi.latched_init == 0)
                                        clear INIT in pending_events

This patch fixes it by not touching INIT pending if INIT is not latched 
which in SMM and just restoring the latched INIT after SET_VCPU_EVENTS.

Thanks Peng Hao for the report and original commit message.

Reported-by: Peng Hao <peng.hao2@zte.com.cn>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
 arch/x86/kvm/x86.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1a4c84d..eaca86d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3164,12 +3164,8 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu,
 			vcpu->arch.hflags |= HF_SMM_INSIDE_NMI_MASK;
 		else
 			vcpu->arch.hflags &= ~HF_SMM_INSIDE_NMI_MASK;
-		if (lapic_in_kernel(vcpu)) {
-			if (events->smi.latched_init)
-				set_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
-			else
-				clear_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
-		}
+		if (events->smi.latched_init && lapic_in_kernel(vcpu))
+			set_bit(KVM_APIC_INIT, &vcpu->arch.apic->pending_events);
 	}
 
 	kvm_make_request(KVM_REQ_EVENT, vcpu);
-- 
2.7.4

             reply	other threads:[~2017-07-30  9:43 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-30  9:42 Wanpeng Li [this message]
2017-08-01 16:27 ` [PATCH] KVM: X86: Fix loss of pending INIT due to race Paolo Bonzini
2017-08-01 22:43   ` Wanpeng Li

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1501407777-2504-1-git-send-email-wanpeng.li@hotmail.com \
    --to=kernellwp@gmail.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pbonzini@redhat.com \
    --cc=rkrcmar@redhat.com \
    --cc=wanpeng.li@hotmail.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.