Bugfixes, including a TLB flush fix that affects processors

without nested page tables.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "Bugfixes, including a TLB flush fix that affects processors without
  nested page tables"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  kvm: fix previous commit for 32-bit builds
  kvm: avoid speculation-based attacks from out-of-range memslot accesses
  KVM: x86: Unload MMU on guest TLB flush if TDP disabled to force MMU sync
  KVM: x86: Ensure liveliness of nested VM-Enter fail tracepoint message
  selftests: kvm: Add support for customized slot0 memory size
  KVM: selftests: introduce P47V64 for s390x
  KVM: x86: Ensure PV TLB flush tracepoint reflects KVM behavior
  KVM: X86: MMU: Use the correct inherited permissions to get shadow page
  KVM: LAPIC: Write 0 to TMICT should also cancel vmx-preemption timer
  KVM: SVM: Fix SEV SEND_START session length & SEND_UPDATE_DATA query length after commit 238eca821c

Documentation/virt/kvm/mmu.rst

@@ -171,8 +171,8 @@ Shadow pages contain the following information:
     shadow pages) so role.quadrant takes values in the range 0..3.  Each
     quadrant maps 1GB virtual address space.
   role.access:
-    Inherited guest access permissions in the form uwx.  Note execute
-    permission is positive, not negative.
+    Inherited guest access permissions from the parent ptes in the form uwx.
+    Note execute permission is positive, not negative.
   role.invalid:
     The page is invalid and should not be used.  It is a root page that is
     currently pinned (by a cpu hardware register pointing to it); once it is

arch/x86/kvm/lapic.c

@@ -1494,6 +1494,15 @@ static void limit_periodic_timer_frequency(struct kvm_lapic *apic)
 
 static void cancel_hv_timer(struct kvm_lapic *apic);
 
+static void cancel_apic_timer(struct kvm_lapic *apic)
+{
+	hrtimer_cancel(&apic->lapic_timer.timer);
+	preempt_disable();
+	if (apic->lapic_timer.hv_timer_in_use)
+		cancel_hv_timer(apic);
+	preempt_enable();
+}
+
 static void apic_update_lvtt(struct kvm_lapic *apic)
 {
 	u32 timer_mode = kvm_lapic_get_reg(apic, APIC_LVTT) &
@@ -1502,11 +1511,7 @@ static void apic_update_lvtt(struct kvm_lapic *apic)
 	if (apic->lapic_timer.timer_mode != timer_mode) {
 		if (apic_lvtt_tscdeadline(apic) != (timer_mode ==
 				APIC_LVT_TIMER_TSCDEADLINE)) {
-			hrtimer_cancel(&apic->lapic_timer.timer);
-			preempt_disable();
-			if (apic->lapic_timer.hv_timer_in_use)
-				cancel_hv_timer(apic);
-			preempt_enable();
+			cancel_apic_timer(apic);
 			kvm_lapic_set_reg(apic, APIC_TMICT, 0);
 			apic->lapic_timer.period = 0;
 			apic->lapic_timer.tscdeadline = 0;
@@ -2092,7 +2097,7 @@ int kvm_lapic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
 		if (apic_lvtt_tscdeadline(apic))
 			break;
 
-		hrtimer_cancel(&apic->lapic_timer.timer);
+		cancel_apic_timer(apic);
 		kvm_lapic_set_reg(apic, APIC_TMICT, val);
 		start_apic_timer(apic);
 		break;

arch/x86/kvm/mmu/paging_tmpl.h

@@ -90,8 +90,8 @@ struct guest_walker {
 	gpa_t pte_gpa[PT_MAX_FULL_LEVELS];
 	pt_element_t __user *ptep_user[PT_MAX_FULL_LEVELS];
 	bool pte_writable[PT_MAX_FULL_LEVELS];
-	unsigned pt_access;
-	unsigned pte_access;
+	unsigned int pt_access[PT_MAX_FULL_LEVELS];
+	unsigned int pte_access;
 	gfn_t gfn;
 	struct x86_exception fault;
 };
@@ -418,13 +418,15 @@ retry_walk:
 		}
 
 		walker->ptes[walker->level - 1] = pte;
+
+		/* Convert to ACC_*_MASK flags for struct guest_walker.  */
+		walker->pt_access[walker->level - 1] = FNAME(gpte_access)(pt_access ^ walk_nx_mask);
 	} while (!is_last_gpte(mmu, walker->level, pte));
 
 	pte_pkey = FNAME(gpte_pkeys)(vcpu, pte);
 	accessed_dirty = have_ad ? pte_access & PT_GUEST_ACCESSED_MASK : 0;
 
 	/* Convert to ACC_*_MASK flags for struct guest_walker.  */
-	walker->pt_access = FNAME(gpte_access)(pt_access ^ walk_nx_mask);
 	walker->pte_access = FNAME(gpte_access)(pte_access ^ walk_nx_mask);
 	errcode = permission_fault(vcpu, mmu, walker->pte_access, pte_pkey, access);
 	if (unlikely(errcode))
@@ -463,7 +465,8 @@ retry_walk:
 	}
 
 	pgprintk("%s: pte %llx pte_access %x pt_access %x\n",
-		 __func__, (u64)pte, walker->pte_access, walker->pt_access);
+		 __func__, (u64)pte, walker->pte_access,
+		 walker->pt_access[walker->level - 1]);
 	return 1;
 
 error:
@@ -643,7 +646,7 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gpa_t addr,
 	bool huge_page_disallowed = exec && nx_huge_page_workaround_enabled;
 	struct kvm_mmu_page *sp = NULL;
 	struct kvm_shadow_walk_iterator it;
-	unsigned direct_access, access = gw->pt_access;
+	unsigned int direct_access, access;
 	int top_level, level, req_level, ret;
 	gfn_t base_gfn = gw->gfn;
 
@@ -675,6 +678,7 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gpa_t addr,
 		sp = NULL;
 		if (!is_shadow_present_pte(*it.sptep)) {
 			table_gfn = gw->table_gfn[it.level - 2];
+			access = gw->pt_access[it.level - 2];
 			sp = kvm_mmu_get_page(vcpu, table_gfn, addr, it.level-1,
 					      false, access);
 		}

arch/x86/kvm/svm/sev.c

@@ -1103,10 +1103,9 @@ __sev_send_start_query_session_length(struct kvm *kvm, struct kvm_sev_cmd *argp,
 	struct sev_data_send_start data;
 	int ret;
 
+	memset(&data, 0, sizeof(data));
 	data.handle = sev->handle;
 	ret = sev_issue_cmd(kvm, SEV_CMD_SEND_START, &data, &argp->error);
-	if (ret < 0)
-		return ret;
 
 	params->session_len = data.session_len;
 	if (copy_to_user((void __user *)(uintptr_t)argp->data, params,
@@ -1215,10 +1214,9 @@ __sev_send_update_data_query_lengths(struct kvm *kvm, struct kvm_sev_cmd *argp,
 	struct sev_data_send_update_data data;
 	int ret;
 
+	memset(&data, 0, sizeof(data));
 	data.handle = sev->handle;
 	ret = sev_issue_cmd(kvm, SEV_CMD_SEND_UPDATE_DATA, &data, &argp->error);
-	if (ret < 0)
-		return ret;
 
 	params->hdr_len = data.hdr_len;
 	params->trans_len = data.trans_len;

arch/x86/kvm/trace.h

@@ -1550,16 +1550,16 @@ TRACE_EVENT(kvm_nested_vmenter_failed,
 	TP_ARGS(msg, err),
 
 	TP_STRUCT__entry(
-		__field(const char *, msg)
+		__string(msg, msg)
 		__field(u32, err)
 	),
 
 	TP_fast_assign(
-		__entry->msg = msg;
+		__assign_str(msg, msg);
 		__entry->err = err;
 	),
 
-	TP_printk("%s%s", __entry->msg, !__entry->err ? "" :
+	TP_printk("%s%s", __get_str(msg), !__entry->err ? "" :
 		__print_symbolic(__entry->err, VMX_VMENTER_INSTRUCTION_ERRORS))
 );
 

arch/x86/kvm/x86.c

@@ -3072,6 +3072,19 @@ static void kvm_vcpu_flush_tlb_all(struct kvm_vcpu *vcpu)
 static void kvm_vcpu_flush_tlb_guest(struct kvm_vcpu *vcpu)
 {
 	++vcpu->stat.tlb_flush;
+
+	if (!tdp_enabled) {
+               /*
+		 * A TLB flush on behalf of the guest is equivalent to
+		 * INVPCID(all), toggling CR4.PGE, etc., which requires
+		 * a forced sync of the shadow page tables.  Unload the
+		 * entire MMU here and the subsequent load will sync the
+		 * shadow page tables, and also flush the TLB.
+		 */
+		kvm_mmu_unload(vcpu);
+		return;
+	}
+
 	static_call(kvm_x86_tlb_flush_guest)(vcpu);
 }
 
@@ -3101,9 +3114,11 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
 	 * expensive IPIs.
 	 */
 	if (guest_pv_has(vcpu, KVM_FEATURE_PV_TLB_FLUSH)) {
+		u8 st_preempted = xchg(&st->preempted, 0);
+
 		trace_kvm_pv_tlb_flush(vcpu->vcpu_id,
-				       st->preempted & KVM_VCPU_FLUSH_TLB);
-		if (xchg(&st->preempted, 0) & KVM_VCPU_FLUSH_TLB)
+				       st_preempted & KVM_VCPU_FLUSH_TLB);
+		if (st_preempted & KVM_VCPU_FLUSH_TLB)
 			kvm_vcpu_flush_tlb_guest(vcpu);
 	} else {
 		st->preempted = 0;

include/linux/kvm_host.h

@@ -1185,7 +1185,15 @@ __gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn)
 static inline unsigned long
 __gfn_to_hva_memslot(const struct kvm_memory_slot *slot, gfn_t gfn)
 {
-	return slot->userspace_addr + (gfn - slot->base_gfn) * PAGE_SIZE;
+	/*
+	 * The index was checked originally in search_memslots.  To avoid
+	 * that a malicious guest builds a Spectre gadget out of e.g. page
+	 * table walks, do not let the processor speculate loads outside
+	 * the guest's registered memslots.
+	 */
+	unsigned long offset = gfn - slot->base_gfn;
+	offset = array_index_nospec(offset, slot->npages);
+	return slot->userspace_addr + offset * PAGE_SIZE;
 }
 
 static inline int memslot_id(struct kvm *kvm, gfn_t gfn)

tools/testing/selftests/kvm/include/kvm_util.h

@@ -43,6 +43,7 @@ enum vm_guest_mode {
 	VM_MODE_P40V48_4K,
 	VM_MODE_P40V48_64K,
 	VM_MODE_PXXV48_4K,	/* For 48bits VA but ANY bits PA */
+	VM_MODE_P47V64_4K,
 	NUM_VM_MODES,
 };
 
@@ -60,7 +61,7 @@ enum vm_guest_mode {
 
 #elif defined(__s390x__)
 
-#define VM_MODE_DEFAULT			VM_MODE_P52V48_4K
+#define VM_MODE_DEFAULT			VM_MODE_P47V64_4K
 #define MIN_PAGE_SHIFT			12U
 #define ptes_per_page(page_size)	((page_size) / 16)
 
@@ -285,10 +286,11 @@ struct kvm_vm *vm_create_default_with_vcpus(uint32_t nr_vcpus, uint64_t extra_me
 					    uint32_t num_percpu_pages, void *guest_code,
 					    uint32_t vcpuids[]);
 
-/* Like vm_create_default_with_vcpus, but accepts mode as a parameter */
+/* Like vm_create_default_with_vcpus, but accepts mode and slot0 memory as a parameter */
 struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
-				    uint64_t extra_mem_pages, uint32_t num_percpu_pages,
-				    void *guest_code, uint32_t vcpuids[]);
+				    uint64_t slot0_mem_pages, uint64_t extra_mem_pages,
+				    uint32_t num_percpu_pages, void *guest_code,
+				    uint32_t vcpuids[]);
 
 /*
  * Adds a vCPU with reasonable defaults (e.g. a stack)

tools/testing/selftests/kvm/kvm_page_table_test.c

@@ -268,7 +268,7 @@ static struct kvm_vm *pre_init_before_test(enum vm_guest_mode mode, void *arg)
 
 	/* Create a VM with enough guest pages */
 	guest_num_pages = test_mem_size / guest_page_size;
-	vm = vm_create_with_vcpus(mode, nr_vcpus,
+	vm = vm_create_with_vcpus(mode, nr_vcpus, DEFAULT_GUEST_PHY_PAGES,
 				  guest_num_pages, 0, guest_code, NULL);
 
 	/* Align down GPA of the testing memslot */

tools/testing/selftests/kvm/lib/kvm_util.c

@@ -175,6 +175,7 @@ const char *vm_guest_mode_string(uint32_t i)
 		[VM_MODE_P40V48_4K]	= "PA-bits:40,  VA-bits:48,  4K pages",
 		[VM_MODE_P40V48_64K]	= "PA-bits:40,  VA-bits:48, 64K pages",
 		[VM_MODE_PXXV48_4K]	= "PA-bits:ANY, VA-bits:48,  4K pages",
+		[VM_MODE_P47V64_4K]	= "PA-bits:47,  VA-bits:64,  4K pages",
 	};
 	_Static_assert(sizeof(strings)/sizeof(char *) == NUM_VM_MODES,
 		       "Missing new mode strings?");
@@ -192,6 +193,7 @@ const struct vm_guest_mode_params vm_guest_mode_params[] = {
 	{ 40, 48,  0x1000, 12 },
 	{ 40, 48, 0x10000, 16 },
 	{  0,  0,  0x1000, 12 },
+	{ 47, 64,  0x1000, 12 },
 };
 _Static_assert(sizeof(vm_guest_mode_params)/sizeof(struct vm_guest_mode_params) == NUM_VM_MODES,
 	       "Missing new mode params?");
@@ -277,6 +279,9 @@ struct kvm_vm *vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm)
 		TEST_FAIL("VM_MODE_PXXV48_4K not supported on non-x86 platforms");
 #endif
 		break;
+	case VM_MODE_P47V64_4K:
+		vm->pgtable_levels = 5;
+		break;
 	default:
 		TEST_FAIL("Unknown guest mode, mode: 0x%x", mode);
 	}
@@ -308,21 +313,50 @@ struct kvm_vm *vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm)
 	return vm;
 }
 
+/*
+ * VM Create with customized parameters
+ *
+ * Input Args:
+ *   mode - VM Mode (e.g. VM_MODE_P52V48_4K)
+ *   nr_vcpus - VCPU count
+ *   slot0_mem_pages - Slot0 physical memory size
+ *   extra_mem_pages - Non-slot0 physical memory total size
+ *   num_percpu_pages - Per-cpu physical memory pages
+ *   guest_code - Guest entry point
+ *   vcpuids - VCPU IDs
+ *
+ * Output Args: None
+ *
+ * Return:
+ *   Pointer to opaque structure that describes the created VM.
+ *
+ * Creates a VM with the mode specified by mode (e.g. VM_MODE_P52V48_4K),
+ * with customized slot0 memory size, at least 512 pages currently.
+ * extra_mem_pages is only used to calculate the maximum page table size,
+ * no real memory allocation for non-slot0 memory in this function.
+ */
 struct kvm_vm *vm_create_with_vcpus(enum vm_guest_mode mode, uint32_t nr_vcpus,
-				    uint64_t extra_mem_pages, uint32_t num_percpu_pages,
-				    void *guest_code, uint32_t vcpuids[])
+				    uint64_t slot0_mem_pages, uint64_t extra_mem_pages,
+				    uint32_t num_percpu_pages, void *guest_code,
+				    uint32_t vcpuids[])
 {
+	uint64_t vcpu_pages, extra_pg_pages, pages;
+	struct kvm_vm *vm;
+	int i;
+
+	/* Force slot0 memory size not small than DEFAULT_GUEST_PHY_PAGES */
+	if (slot0_mem_pages < DEFAULT_GUEST_PHY_PAGES)
+		slot0_mem_pages = DEFAULT_GUEST_PHY_PAGES;
+
 	/* The maximum page table size for a memory region will be when the
 	 * smallest pages are used. Considering each page contains x page
 	 * table descriptors, the total extra size for page tables (for extra
 	 * N pages) will be: N/x+N/x^2+N/x^3+... which is definitely smaller
 	 * than N/x*2.
 	 */
-	uint64_t vcpu_pages = (DEFAULT_STACK_PGS + num_percpu_pages) * nr_vcpus;
-	uint64_t extra_pg_pages = (extra_mem_pages + vcpu_pages) / PTES_PER_MIN_PAGE * 2;
-	uint64_t pages = DEFAULT_GUEST_PHY_PAGES + extra_mem_pages + vcpu_pages + extra_pg_pages;
-	struct kvm_vm *vm;
-	int i;
+	vcpu_pages = (DEFAULT_STACK_PGS + num_percpu_pages) * nr_vcpus;
+	extra_pg_pages = (slot0_mem_pages + extra_mem_pages + vcpu_pages) / PTES_PER_MIN_PAGE * 2;
+	pages = slot0_mem_pages + vcpu_pages + extra_pg_pages;
 
 	TEST_ASSERT(nr_vcpus <= kvm_check_cap(KVM_CAP_MAX_VCPUS),
 		    "nr_vcpus = %d too large for host, max-vcpus = %d",
@@ -354,8 +388,8 @@ struct kvm_vm *vm_create_default_with_vcpus(uint32_t nr_vcpus, uint64_t extra_me
 					    uint32_t num_percpu_pages, void *guest_code,
 					    uint32_t vcpuids[])
 {
-	return vm_create_with_vcpus(VM_MODE_DEFAULT, nr_vcpus, extra_mem_pages,
-				    num_percpu_pages, guest_code, vcpuids);
+	return vm_create_with_vcpus(VM_MODE_DEFAULT, nr_vcpus, DEFAULT_GUEST_PHY_PAGES,
+				    extra_mem_pages, num_percpu_pages, guest_code, vcpuids);
 }
 
 struct kvm_vm *vm_create_default(uint32_t vcpuid, uint64_t extra_mem_pages,

tools/testing/selftests/kvm/lib/perf_test_util.c

@@ -69,7 +69,7 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int vcpus,
 	TEST_ASSERT(vcpu_memory_bytes % perf_test_args.guest_page_size == 0,
 		    "Guest memory size is not guest page size aligned.");
 
-	vm = vm_create_with_vcpus(mode, vcpus,
+	vm = vm_create_with_vcpus(mode, vcpus, DEFAULT_GUEST_PHY_PAGES,
 				  (vcpus * vcpu_memory_bytes) / perf_test_args.guest_page_size,
 				  0, guest_code, NULL);
 

tools/testing/selftests/kvm/memslot_perf_test.c

@@ -267,7 +267,7 @@ static bool prepare_vm(struct vm_data *data, int nslots, uint64_t *maxslots,
 	data->hva_slots = malloc(sizeof(*data->hva_slots) * data->nslots);
 	TEST_ASSERT(data->hva_slots, "malloc() fail");
 
-	data->vm = vm_create_default(VCPU_ID, 1024, guest_code);
+	data->vm = vm_create_default(VCPU_ID, mempages, guest_code);
 
 	pr_info_v("Adding slots 1..%i, each slot with %"PRIu64" pages + %"PRIu64" extra pages last\n",
 		max_mem_slots - 1, data->pages_per_slot, rempages);