[PATCH 0/9] KVM: Flush out my patch queue

[PATCH 0/9] KVM: Flush out my patch queue

[Avi Kivity]

This patchset is mostly fallout from the mmu stuff that I've neglected 
to integrate with the main patchset sent yesterday.  It includes a 
fashionable missing dirty bit fix, and other fixes and cleanups.

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


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[PATCH 1/9] KVM: Improve reporting of vmwrite errors

[Avi Kivity]

This will allow us to see the root cause when a vmwrite error happens.

Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Index: linux-2.6/drivers/kvm/vmx.c
===================================================================
--- linux-2.6.orig/drivers/kvm/vmx.c
+++ linux-2.6/drivers/kvm/vmx.c
@@ -152,15 +152,21 @@ static u64 vmcs_read64(unsigned long fie
 #endif
 }
 
+static noinline void vmwrite_error(unsigned long field, unsigned long value)
+{
+	printk(KERN_ERR "vmwrite error: reg %lx value %lx (err %d)\n",
+	       field, value, vmcs_read32(VM_INSTRUCTION_ERROR));
+	dump_stack();
+}
+
 static void vmcs_writel(unsigned long field, unsigned long value)
 {
 	u8 error;
 
 	asm volatile (ASM_VMX_VMWRITE_RAX_RDX "; setna %0"
 		       : "=q"(error) : "a"(value), "d"(field) : "cc" );
-	if (error)
-		printk(KERN_ERR "vmwrite error: reg %lx value %lx (err %d)\n",
-		       field, value, vmcs_read32(VM_INSTRUCTION_ERROR));
+	if (unlikely(error))
+		vmwrite_error(field, value);
 }
 
 static void vmcs_write16(unsigned long field, u16 value)

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[PATCH 2/9] KVM: Initialize vcpu->kvm a little earlier

[Avi Kivity]

Fixes oops on early close of /dev/kvm.

Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Index: linux-2.6/drivers/kvm/kvm_main.c
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm_main.c
+++ linux-2.6/drivers/kvm/kvm_main.c
@@ -230,6 +230,7 @@ static int kvm_dev_open(struct inode *in
 		struct kvm_vcpu *vcpu = &kvm->vcpus[i];
 
 		mutex_init(&vcpu->mutex);
+		vcpu->kvm = kvm;
 		vcpu->mmu.root_hpa = INVALID_PAGE;
 		INIT_LIST_HEAD(&vcpu->free_pages);
 	}
@@ -530,7 +531,6 @@ static int kvm_dev_ioctl_create_vcpu(str
 	vcpu->guest_fx_image = vcpu->host_fx_image + FX_IMAGE_SIZE;
 
 	vcpu->cpu = -1;  /* First load will set up TR */
-	vcpu->kvm = kvm;
 	r = kvm_arch_ops->vcpu_create(vcpu);
 	if (r < 0)
 		goto out_free_vcpus;

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[PATCH 3/9] KVM: Avoid oom on cr3 switch

[Avi Kivity]

From: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>

Signed-off-by: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>
Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Index: linux-2.6/drivers/kvm/mmu.c
===================================================================
--- linux-2.6.orig/drivers/kvm/mmu.c
+++ linux-2.6/drivers/kvm/mmu.c
@@ -905,6 +905,8 @@ static void paging_new_cr3(struct kvm_vc
 {
 	pgprintk("%s: cr3 %lx\n", __FUNCTION__, vcpu->cr3);
 	mmu_free_roots(vcpu);
+	if (unlikely(vcpu->kvm->n_free_mmu_pages < KVM_MIN_FREE_MMU_PAGES))
+		kvm_mmu_free_some_pages(vcpu);
 	mmu_alloc_roots(vcpu);
 	kvm_mmu_flush_tlb(vcpu);
 	kvm_arch_ops->set_cr3(vcpu, vcpu->mmu.root_hpa);

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[PATCH 4/9] KVM: Add missing 'break'

[Avi Kivity]

Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Index: linux-2.6/drivers/kvm/kvm_main.c
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm_main.c
+++ linux-2.6/drivers/kvm/kvm_main.c
@@ -1922,6 +1922,7 @@ static long kvm_dev_ioctl(struct file *f
 				 num_msrs_to_save * sizeof(u32)))
 			goto out;
 		r = 0;
+		break;
 	}
 	default:
 		;

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[PATCH 5/9] KVM: Don't set guest cr3 from vmx_vcpu_setup()

[Avi Kivity]

It overwrites the right cr3 set from mmu setup.  Happens only with the test harness.

Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Index: linux-2.6/drivers/kvm/vmx.c
===================================================================
--- linux-2.6.orig/drivers/kvm/vmx.c
+++ linux-2.6/drivers/kvm/vmx.c
@@ -1027,8 +1027,6 @@ static int vmx_vcpu_setup(struct kvm_vcp
 	vmcs_writel(GUEST_RIP, 0xfff0);
 	vmcs_writel(GUEST_RSP, 0);
 
-	vmcs_writel(GUEST_CR3, 0);
-
 	//todo: dr0 = dr1 = dr2 = dr3 = 0; dr6 = 0xffff0ff0
 	vmcs_writel(GUEST_DR7, 0x400);
 

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[PATCH 6/9] KVM: MMU: Add missing dirty bit

[Avi Kivity]

If we emulate a write, we fail to set the dirty bit on the guest pte, leading
the guest to believe the page is clean, and thus lose data.  Bad.

Fix by setting the guest pte dirty bit under such conditions.

Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Index: linux-2.6/drivers/kvm/paging_tmpl.h
===================================================================
--- linux-2.6.orig/drivers/kvm/paging_tmpl.h
+++ linux-2.6/drivers/kvm/paging_tmpl.h
@@ -317,6 +317,7 @@ static int FNAME(fix_write_pf)(struct kv
 	} else if (kvm_mmu_lookup_page(vcpu, gfn)) {
 		pgprintk("%s: found shadow page for %lx, marking ro\n",
 			 __FUNCTION__, gfn);
+		*guest_ent |= PT_DIRTY_MASK;
 		*write_pt = 1;
 		return 0;
 	}

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[PATCH 7/9] KVM: Make loading cr3 more robust

[Avi Kivity]

From: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>

Prevent the guest's loading of a corrupt cr3 (pointing at no guest phsyical
page) from crashing the host.

Signed-off-by: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>
Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Index: linux-2.6/drivers/kvm/kvm_main.c
===================================================================
--- linux-2.6.orig/drivers/kvm/kvm_main.c
+++ linux-2.6/drivers/kvm/kvm_main.c
@@ -463,7 +463,19 @@ void set_cr3(struct kvm_vcpu *vcpu, unsi
 
 	vcpu->cr3 = cr3;
 	spin_lock(&vcpu->kvm->lock);
-	vcpu->mmu.new_cr3(vcpu);
+	/*
+	 * Does the new cr3 value map to physical memory? (Note, we
+	 * catch an invalid cr3 even in real-mode, because it would
+	 * cause trouble later on when we turn on paging anyway.)
+	 *
+	 * A real CPU would silently accept an invalid cr3 and would
+	 * attempt to use it - with largely undefined (and often hard
+	 * to debug) behavior on the guest side.
+	 */
+	if (unlikely(!gfn_to_memslot(vcpu->kvm, cr3 >> PAGE_SHIFT)))
+		inject_gp(vcpu);
+	else
+		vcpu->mmu.new_cr3(vcpu);
 	spin_unlock(&vcpu->kvm->lock);
 }
 EXPORT_SYMBOL_GPL(set_cr3);

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[PATCH 8/9] KVM: Simplify mmu_alloc_roots()

[Avi Kivity]

From: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>

Small optimization/cleanup:

    page == page_header(page->page_hpa)

Signed-off-by: Ingo Molnar <mingo-X9Un+BFzKDI@public.gmane.org>
Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Index: linux-2.6/drivers/kvm/mmu.c
===================================================================
--- linux-2.6.orig/drivers/kvm/mmu.c
+++ linux-2.6/drivers/kvm/mmu.c
@@ -820,9 +820,9 @@ static void mmu_alloc_roots(struct kvm_v
 		hpa_t root = vcpu->mmu.root_hpa;
 
 		ASSERT(!VALID_PAGE(root));
-		root = kvm_mmu_get_page(vcpu, root_gfn, 0,
-					PT64_ROOT_LEVEL, 0, NULL)->page_hpa;
-		page = page_header(root);
+		page = kvm_mmu_get_page(vcpu, root_gfn, 0,
+					PT64_ROOT_LEVEL, 0, NULL);
+		root = page->page_hpa;
 		++page->root_count;
 		vcpu->mmu.root_hpa = root;
 		return;
@@ -836,10 +836,10 @@ static void mmu_alloc_roots(struct kvm_v
 			root_gfn = vcpu->pdptrs[i] >> PAGE_SHIFT;
 		else if (vcpu->mmu.root_level == 0)
 			root_gfn = 0;
-		root = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
+		page = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
 					PT32_ROOT_LEVEL, !is_paging(vcpu),
-					NULL)->page_hpa;
-		page = page_header(root);
+					NULL);
+		root = page->page_hpa;
 		++page->root_count;
 		vcpu->mmu.pae_root[i] = root | PT_PRESENT_MASK;
 	}

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[PATCH 9/9] KVM: Simplify test for interrupt window

[Avi Kivity]

No need to test for rflags.if as both VT and SVM specs assure us that on exit caused from
interrupt window opening, 'if' is set.

Signed-off-by: Dor Laor <dor.laor-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
Signed-off-by: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>

Index: linux-2.6/drivers/kvm/svm.c
===================================================================
--- linux-2.6.orig/drivers/kvm/svm.c
+++ linux-2.6/drivers/kvm/svm.c
@@ -1206,8 +1206,7 @@ static int interrupt_window_interception
 	 * possible
 	 */
 	if (kvm_run->request_interrupt_window &&
-	    !vcpu->irq_summary &&
-	    (vcpu->svm->vmcb->save.rflags & X86_EFLAGS_IF)) {
+	    !vcpu->irq_summary) {
 		++kvm_stat.irq_window_exits;
 		kvm_run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
 		return 0;
Index: linux-2.6/drivers/kvm/vmx.c
===================================================================
--- linux-2.6.orig/drivers/kvm/vmx.c
+++ linux-2.6/drivers/kvm/vmx.c
@@ -1604,8 +1604,7 @@ static int handle_interrupt_window(struc
 	 * possible
 	 */
 	if (kvm_run->request_interrupt_window &&
-	    !vcpu->irq_summary &&
-	    (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF)) {
+	    !vcpu->irq_summary) {
 		kvm_run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
 		++kvm_stat.irq_window_exits;
 		return 0;

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