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Patch "kvm: async_pf: fix rcu_irq_enter() with irqs enabled" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Jun 12, 2017

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This is a note to let you know that I've just added the patch titled

kvm: async_pf: fix rcu_irq_enter() with irqs enabled

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
kvm-async_pf-fix-rcu_irq_enter-with-irqs-enabled.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From bbaf0e2b1c1b4f88abd6ef49576f0efb1734eae5 Mon Sep 17 00:00:00 2001

From: Paolo Bonzini <[email protected]>
Date: Wed, 26 Apr 2017 16:56:26 +0200
Subject: kvm: async_pf: fix rcu_irq_enter() with irqs enabled
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Paolo Bonzini <[email protected]>

commit bbaf0e2b1c1b4f88abd6ef49576f0efb1734eae5 upstream.

native_safe_halt enables interrupts, and you just shouldn't call rcu_irq_enter() with interrupts enabled. Reorder the call with the following local_irq_disable() to respect the invariant.

---
 arch/x86/kernel/kvm.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
arch/x86/kernel/kvm.c +1 -1
@@ -162,8 +162,8 @@ void kvm_async_pf_task_wait(u32 token)
 			 */
 			rcu_irq_exit();
 			native_safe_halt();
-			rcu_irq_enter();
 			local_irq_disable();
+			rcu_irq_enter();
 		}
 	}
 	if (!n.halted)

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/kvm-async_pf-fix-rcu_irq_enter-with-irqs-enabled.patch queue-4.9/kvm-async_pf-avoid-async-pf-injection-when-in-guest-mode.patch queue-4.9/kvm-cpuid-fix-read-write-out-of-bounds-vulnerability-in-cpuid-emulation.patch