Re: kvm-intel kernel panicing 2.6.22 on T7200

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

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Magicboiz wrote:
> with VNC option, we had better luck: we got an Oops!!:
>
> Jun 14 17:37:35 linux kernel: [  575.212000] BUG: unable to handle
> kernel NULL pointer dereference at virtual address 00000024
> Jun 14 17:37:35 linux kernel: [  575.212000] EIP is at mmu_free_roots
> +0x54/0x90 [kvm]
>   


Does the attached patch help?  (cd to kernel/ and apply with 'patch -p3')

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


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diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index ad50cfd..f4cb731 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -859,7 +859,7 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
 			page = page_header(root);
 			--page->root_count;
 		}
-		vcpu->mmu.pae_root[i] = INVALID_PAGE;
+		vcpu->mmu.pae_root[i] = 0;
 	}
 	vcpu->mmu.root_hpa = INVALID_PAGE;
 }
@@ -888,12 +888,10 @@ static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
 	for (i = 0; i < 4; ++i) {
 		hpa_t root = vcpu->mmu.pae_root[i];
 
-		ASSERT(!VALID_PAGE(root));
+		ASSERT(!root);
 		if (vcpu->mmu.root_level == PT32E_ROOT_LEVEL) {
-			if (!is_present_pte(vcpu->pdptrs[i])) {
-				vcpu->mmu.pae_root[i] = 0;
+			if (!is_present_pte(vcpu->pdptrs[i]))
 				continue;
-			}
 			root_gfn = vcpu->pdptrs[i] >> PAGE_SHIFT;
 		} else if (vcpu->mmu.root_level == 0)
 			root_gfn = 0;
@@ -1241,7 +1239,7 @@ static int alloc_mmu_pages(struct kvm_vcpu *vcpu)
 		goto error_1;
 	vcpu->mmu.pae_root = page_address(page);
 	for (i = 0; i < 4; ++i)
-		vcpu->mmu.pae_root[i] = INVALID_PAGE;
+		vcpu->mmu.pae_root[i] = 0;
 
 	return 0;
 

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