linux-kernel - [PATCH 10/46] Revert "KVM: x86: check for cr3 validity in ioctl_set

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Message-Id: <1251028605-31977-11-git-send-email-avi@redhat.com>
Date:	Sun, 23 Aug 2009 14:56:09 +0300
From:	Avi Kivity <avi@...hat.com>
To:	kvm@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 10/46] Revert "KVM: x86: check for cr3 validity in ioctl_set_sregs"

From: Jan Kiszka <jan.kiszka@....de>

This reverts commit 6c20e1442bb1c62914bb85b7f4a38973d2a423ba.

To my understanding, it became obsolete with the advent of the more
robust check in mmu_alloc_roots (89da4ff17f). Moreover, it prevents
the conceptually safe pattern

 1. set sregs
 2. register mem-slots
 3. run vcpu

by setting a sticky triple fault during step 1.

Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
Signed-off-by: Avi Kivity <avi@...hat.com>
---
 arch/x86/kvm/x86.c |    8 +-------
 1 files changed, 1 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6dde99c..0e74d98 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4326,13 +4326,7 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
 
 	vcpu->arch.cr2 = sregs->cr2;
 	mmu_reset_needed |= vcpu->arch.cr3 != sregs->cr3;
-
-	down_read(&vcpu->kvm->slots_lock);
-	if (gfn_to_memslot(vcpu->kvm, sregs->cr3 >> PAGE_SHIFT))
-		vcpu->arch.cr3 = sregs->cr3;
-	else
-		set_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests);
-	up_read(&vcpu->kvm->slots_lock);
+	vcpu->arch.cr3 = sregs->cr3;
 
 	kvm_set_cr8(vcpu, sregs->cr8);
 
-- 
1.6.4.1

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