x86 fixes for overflows and other nastiness.

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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "x86 fixes for overflows and other nastiness"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86: nVMX: fix x2APIC VTPR read intercept
  KVM: x86: nVMX: close leak of L0's x2APIC MSRs (CVE-2019-3887)
  KVM: SVM: prevent DBG_DECRYPT and DBG_ENCRYPT overflow
  kvm: svm: fix potential get_num_contig_pages overflow

arch/x86/kvm/svm.c

@@ -6422,11 +6422,11 @@ e_free:
 	return ret;
 }
 
-static int get_num_contig_pages(int idx, struct page **inpages,
-				unsigned long npages)
+static unsigned long get_num_contig_pages(unsigned long idx,
+				struct page **inpages, unsigned long npages)
 {
 	unsigned long paddr, next_paddr;
-	int i = idx + 1, pages = 1;
+	unsigned long i = idx + 1, pages = 1;
 
 	/* find the number of contiguous pages starting from idx */
 	paddr = __sme_page_pa(inpages[idx]);
@@ -6445,12 +6445,12 @@ static int get_num_contig_pages(int idx, struct page **inpages,
 
 static int sev_launch_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
 {
-	unsigned long vaddr, vaddr_end, next_vaddr, npages, size;
+	unsigned long vaddr, vaddr_end, next_vaddr, npages, pages, size, i;
 	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
 	struct kvm_sev_launch_update_data params;
 	struct sev_data_launch_update_data *data;
 	struct page **inpages;
-	int i, ret, pages;
+	int ret;
 
 	if (!sev_guest(kvm))
 		return -ENOTTY;
@@ -6799,7 +6799,8 @@ static int sev_dbg_crypt(struct kvm *kvm, struct kvm_sev_cmd *argp, bool dec)
 	struct page **src_p, **dst_p;
 	struct kvm_sev_dbg debug;
 	unsigned long n;
-	int ret, size;
+	unsigned int size;
+	int ret;
 
 	if (!sev_guest(kvm))
 		return -ENOTTY;
@@ -6807,6 +6808,11 @@ static int sev_dbg_crypt(struct kvm *kvm, struct kvm_sev_cmd *argp, bool dec)
 	if (copy_from_user(&debug, (void __user *)(uintptr_t)argp->data, sizeof(debug)))
 		return -EFAULT;
 
+	if (!debug.len || debug.src_uaddr + debug.len < debug.src_uaddr)
+		return -EINVAL;
+	if (!debug.dst_uaddr)
+		return -EINVAL;
+
 	vaddr = debug.src_uaddr;
 	size = debug.len;
 	vaddr_end = vaddr + size;
@@ -6857,8 +6863,8 @@ static int sev_dbg_crypt(struct kvm *kvm, struct kvm_sev_cmd *argp, bool dec)
 						     dst_vaddr,
 						     len, &argp->error);
 
-		sev_unpin_memory(kvm, src_p, 1);
-		sev_unpin_memory(kvm, dst_p, 1);
+		sev_unpin_memory(kvm, src_p, n);
+		sev_unpin_memory(kvm, dst_p, n);
 
 		if (ret)
 			goto err;

arch/x86/kvm/vmx/nested.c

@@ -500,6 +500,17 @@ static void nested_vmx_disable_intercept_for_msr(unsigned long *msr_bitmap_l1,
 	}
 }
 
+static inline void enable_x2apic_msr_intercepts(unsigned long *msr_bitmap) {
+	int msr;
+
+	for (msr = 0x800; msr <= 0x8ff; msr += BITS_PER_LONG) {
+		unsigned word = msr / BITS_PER_LONG;
+
+		msr_bitmap[word] = ~0;
+		msr_bitmap[word + (0x800 / sizeof(long))] = ~0;
+	}
+}
+
 /*
  * Merge L0's and L1's MSR bitmap, return false to indicate that
  * we do not use the hardware.
@@ -541,39 +552,44 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu,
 		return false;
 
 	msr_bitmap_l1 = (unsigned long *)kmap(page);
-	if (nested_cpu_has_apic_reg_virt(vmcs12)) {
-		/*
-		 * L0 need not intercept reads for MSRs between 0x800 and 0x8ff, it
-		 * just lets the processor take the value from the virtual-APIC page;
-		 * take those 256 bits directly from the L1 bitmap.
-		 */
-		for (msr = 0x800; msr <= 0x8ff; msr += BITS_PER_LONG) {
-			unsigned word = msr / BITS_PER_LONG;
-			msr_bitmap_l0[word] = msr_bitmap_l1[word];
-			msr_bitmap_l0[word + (0x800 / sizeof(long))] = ~0;
-		}
-	} else {
-		for (msr = 0x800; msr <= 0x8ff; msr += BITS_PER_LONG) {
-			unsigned word = msr / BITS_PER_LONG;
-			msr_bitmap_l0[word] = ~0;
-			msr_bitmap_l0[word + (0x800 / sizeof(long))] = ~0;
-		}
-	}
 
-	nested_vmx_disable_intercept_for_msr(
-		msr_bitmap_l1, msr_bitmap_l0,
-		X2APIC_MSR(APIC_TASKPRI),
-		MSR_TYPE_W);
+	/*
+	 * To keep the control flow simple, pay eight 8-byte writes (sixteen
+	 * 4-byte writes on 32-bit systems) up front to enable intercepts for
+	 * the x2APIC MSR range and selectively disable them below.
+	 */
+	enable_x2apic_msr_intercepts(msr_bitmap_l0);
+
+	if (nested_cpu_has_virt_x2apic_mode(vmcs12)) {
+		if (nested_cpu_has_apic_reg_virt(vmcs12)) {
+			/*
+			 * L0 need not intercept reads for MSRs between 0x800
+			 * and 0x8ff, it just lets the processor take the value
+			 * from the virtual-APIC page; take those 256 bits
+			 * directly from the L1 bitmap.
+			 */
+			for (msr = 0x800; msr <= 0x8ff; msr += BITS_PER_LONG) {
+				unsigned word = msr / BITS_PER_LONG;
+
+				msr_bitmap_l0[word] = msr_bitmap_l1[word];
+			}
+		}
 
-	if (nested_cpu_has_vid(vmcs12)) {
 		nested_vmx_disable_intercept_for_msr(
 			msr_bitmap_l1, msr_bitmap_l0,
-			X2APIC_MSR(APIC_EOI),
-			MSR_TYPE_W);
-		nested_vmx_disable_intercept_for_msr(
-			msr_bitmap_l1, msr_bitmap_l0,
-			X2APIC_MSR(APIC_SELF_IPI),
-			MSR_TYPE_W);
+			X2APIC_MSR(APIC_TASKPRI),
+			MSR_TYPE_R | MSR_TYPE_W);
+
+		if (nested_cpu_has_vid(vmcs12)) {
+			nested_vmx_disable_intercept_for_msr(
+				msr_bitmap_l1, msr_bitmap_l0,
+				X2APIC_MSR(APIC_EOI),
+				MSR_TYPE_W);
+			nested_vmx_disable_intercept_for_msr(
+				msr_bitmap_l1, msr_bitmap_l0,
+				X2APIC_MSR(APIC_SELF_IPI),
+				MSR_TYPE_W);
+		}
 	}
 
 	if (spec_ctrl)