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

Pull KVM fixes from Radim Krčmář:
 "s390:
   - Two fixes for potential bitmap overruns in the cmma migration code

  x86:
   - Clear guest provided GPRs to defeat the Project Zero PoC for CVE
     2017-5715"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  kvm: vmx: Scrub hardware GPRs at VM-exit
  KVM: s390: prevent buffer overrun on memory hotplug during migration
  KVM: s390: fix cmma migration for multiple memory slots

4 files changed, 38 insertions, 6 deletions

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index ec8b68e97d3c..2c93cbbcd15e 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -792,11 +792,12 @@ static int kvm_s390_vm_start_migration(struct kvm *kvm)
 
 	if (kvm->arch.use_cmma) {
 		/*
-		 * Get the last slot. They should be sorted by base_gfn, so the
-		 * last slot is also the one at the end of the address space.
-		 * We have verified above that at least one slot is present.
+		 * Get the first slot. They are reverse sorted by base_gfn, so
+		 * the first slot is also the one at the end of the address
+		 * space. We have verified above that at least one slot is
+		 * present.
 		 */
-		ms = slots->memslots + slots->used_slots - 1;
+		ms = slots->memslots;
 		/* round up so we only use full longs */
 		ram_pages = roundup(ms->base_gfn + ms->npages, BITS_PER_LONG);
 		/* allocate enough bytes to store all the bits */
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 572496c688cc..0714bfa56da0 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -1006,7 +1006,7 @@ static inline int do_essa(struct kvm_vcpu *vcpu, const int orc)
 		cbrlo[entries] = gfn << PAGE_SHIFT;
 	}
 
-	if (orc) {
+	if (orc && gfn < ms->bitmap_size) {
 		/* increment only if we are really flipping the bit to 1 */
 		if (!test_and_set_bit(gfn, ms->pgste_bitmap))
 			atomic64_inc(&ms->dirty_pages);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index eb714f1cdf7e..bb31c801f1fc 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -4986,6 +4986,25 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
 		"mov %%r14, %c[r14](%[svm]) \n\t"
 		"mov %%r15, %c[r15](%[svm]) \n\t"
 #endif
+		/*
+		* Clear host registers marked as clobbered to prevent
+		* speculative use.
+		*/
+		"xor %%" _ASM_BX ", %%" _ASM_BX " \n\t"
+		"xor %%" _ASM_CX ", %%" _ASM_CX " \n\t"
+		"xor %%" _ASM_DX ", %%" _ASM_DX " \n\t"
+		"xor %%" _ASM_SI ", %%" _ASM_SI " \n\t"
+		"xor %%" _ASM_DI ", %%" _ASM_DI " \n\t"
+#ifdef CONFIG_X86_64
+		"xor %%r8, %%r8 \n\t"
+		"xor %%r9, %%r9 \n\t"
+		"xor %%r10, %%r10 \n\t"
+		"xor %%r11, %%r11 \n\t"
+		"xor %%r12, %%r12 \n\t"
+		"xor %%r13, %%r13 \n\t"
+		"xor %%r14, %%r14 \n\t"
+		"xor %%r15, %%r15 \n\t"
+#endif
 		"pop %%" _ASM_BP
 		:
 		: [svm]"a"(svm),
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 023afa0c8887..5c14d65f676a 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -9415,6 +9415,7 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
 		/* Save guest registers, load host registers, keep flags */
 		"mov %0, %c[wordsize](%%" _ASM_SP ") \n\t"
 		"pop %0 \n\t"
+		"setbe %c[fail](%0)\n\t"
 		"mov %%" _ASM_AX ", %c[rax](%0) \n\t"
 		"mov %%" _ASM_BX ", %c[rbx](%0) \n\t"
 		__ASM_SIZE(pop) " %c[rcx](%0) \n\t"
@@ -9431,12 +9432,23 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
 		"mov %%r13, %c[r13](%0) \n\t"
 		"mov %%r14, %c[r14](%0) \n\t"
 		"mov %%r15, %c[r15](%0) \n\t"
+		"xor %%r8d,  %%r8d \n\t"
+		"xor %%r9d,  %%r9d \n\t"
+		"xor %%r10d, %%r10d \n\t"
+		"xor %%r11d, %%r11d \n\t"
+		"xor %%r12d, %%r12d \n\t"
+		"xor %%r13d, %%r13d \n\t"
+		"xor %%r14d, %%r14d \n\t"
+		"xor %%r15d, %%r15d \n\t"
 #endif
 		"mov %%cr2, %%" _ASM_AX "   \n\t"
 		"mov %%" _ASM_AX ", %c[cr2](%0) \n\t"
 
+		"xor %%eax, %%eax \n\t"
+		"xor %%ebx, %%ebx \n\t"
+		"xor %%esi, %%esi \n\t"
+		"xor %%edi, %%edi \n\t"
 		"pop  %%" _ASM_BP "; pop  %%" _ASM_DX " \n\t"
-		"setbe %c[fail](%0) \n\t"
 		".pushsection .rodata \n\t"
 		".global vmx_return \n\t"
 		"vmx_return: " _ASM_PTR " 2b \n\t"