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

Pull kvm fixes from Paolo Bonzini:
 "s390:
   - vsie: Fix races with partial gmap invalidations

  x86:
   - Use __DECLARE_FLEX_ARRAY() for UAPI structures with VLAs"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: s390: vsie: Fix races with partial gmap invalidations
  KVM: x86: Use __DECLARE_FLEX_ARRAY() for UAPI structures with VLAs

Author: torvalds

arch/s390/kvm/gaccess.c

@@ -1449,7 +1449,7 @@ static int _do_shadow_pte(struct gmap *sg, gpa_t raddr, union pte *ptep_h, union
 	pgste_set_unlock(ptep_h, pgste);
 	if (rc)
 		return rc;
-	if (!sg->parent)
+	if (sg->invalidated)
 		return -EAGAIN;
 
 	newpte = _pte(f->pfn, 0, !p, 0);
@@ -1479,7 +1479,7 @@ static int _do_shadow_crste(struct gmap *sg, gpa_t raddr, union crste *host, uni
 
 	do {
 		/* _gmap_crstep_xchg_atomic() could have unshadowed this shadow gmap */
-		if (!sg->parent)
+		if (sg->invalidated)
 			return -EAGAIN;
 		oldcrste = READ_ONCE(*host);
 		newcrste = _crste_fc1(f->pfn, oldcrste.h.tt, f->writable, !p);
@@ -1492,7 +1492,7 @@ static int _do_shadow_crste(struct gmap *sg, gpa_t raddr, union crste *host, uni
 		if (!newcrste.h.p && !f->writable)
 			return -EOPNOTSUPP;
 	} while (!_gmap_crstep_xchg_atomic(sg->parent, host, oldcrste, newcrste, f->gfn, false));
-	if (!sg->parent)
+	if (sg->invalidated)
 		return -EAGAIN;
 
 	newcrste = _crste_fc1(f->pfn, oldcrste.h.tt, 0, !p);
@@ -1545,7 +1545,7 @@ static int _gaccess_do_shadow(struct kvm_s390_mmu_cache *mc, struct gmap *sg,
 				       entries[i].pfn, i + 1, entries[i].writable);
 		if (rc)
 			return rc;
-		if (!sg->parent)
+		if (sg->invalidated)
 			return -EAGAIN;
 	}
 
@@ -1601,6 +1601,7 @@ static inline int _gaccess_shadow_fault(struct kvm_vcpu *vcpu, struct gmap *sg,
 		scoped_guard(spinlock, &parent->children_lock) {
 			if (READ_ONCE(sg->parent) != parent)
 				return -EAGAIN;
+			sg->invalidated = false;
 			rc = _gaccess_do_shadow(vcpu->arch.mc, sg, saddr, walk);
 		}
 		if (rc == -ENOMEM)

arch/s390/kvm/gmap.c

@@ -181,6 +181,7 @@ void gmap_remove_child(struct gmap *child)
 
 	list_del(&child->list);
 	child->parent = NULL;
+	child->invalidated = true;
 }
 
 /**
@@ -1069,6 +1070,7 @@ static void gmap_unshadow_level(struct gmap *sg, gfn_t r_gfn, int level)
 	if (level > TABLE_TYPE_PAGE_TABLE)
 		align = 1UL << (11 * level + _SEGMENT_SHIFT);
 	kvm_s390_vsie_gmap_notifier(sg, ALIGN_DOWN(gaddr, align), ALIGN(gaddr + 1, align));
+	sg->invalidated = true;
 	if (dat_entry_walk(NULL, r_gfn, sg->asce, 0, level, &crstep, &ptep))
 		return;
 	if (ptep) {
@@ -1174,6 +1176,7 @@ static inline int __gmap_protect_asce_top_level(struct kvm_s390_mmu_cache *mc, s
 	scoped_guard(spinlock, &parent->children_lock) {
 		if (READ_ONCE(sg->parent) != parent)
 			return -EAGAIN;
+		sg->invalidated = false;
 		for (i = 0; i < CRST_TABLE_PAGES; i++) {
 			if (!context->f[i].valid)
 				continue;

arch/s390/kvm/gmap.h

@@ -60,6 +60,7 @@ enum gmap_flags {
 struct gmap {
 	unsigned long flags;
 	unsigned char edat_level;
+	bool invalidated;
 	struct kvm *kvm;
 	union asce asce;
 	struct list_head list;

arch/x86/include/uapi/asm/kvm.h

@@ -197,13 +197,13 @@ struct kvm_msrs {
 	__u32 nmsrs; /* number of msrs in entries */
 	__u32 pad;
 
-	struct kvm_msr_entry entries[];
+	__DECLARE_FLEX_ARRAY(struct kvm_msr_entry, entries);
 };
 
 /* for KVM_GET_MSR_INDEX_LIST */
 struct kvm_msr_list {
 	__u32 nmsrs; /* number of msrs in entries */
-	__u32 indices[];
+	__DECLARE_FLEX_ARRAY(__u32, indices);
 };
 
 /* Maximum size of any access bitmap in bytes */
@@ -245,7 +245,7 @@ struct kvm_cpuid_entry {
 struct kvm_cpuid {
 	__u32 nent;
 	__u32 padding;
-	struct kvm_cpuid_entry entries[];
+	__DECLARE_FLEX_ARRAY(struct kvm_cpuid_entry, entries);
 };
 
 struct kvm_cpuid_entry2 {
@@ -267,7 +267,7 @@ struct kvm_cpuid_entry2 {
 struct kvm_cpuid2 {
 	__u32 nent;
 	__u32 padding;
-	struct kvm_cpuid_entry2 entries[];
+	__DECLARE_FLEX_ARRAY(struct kvm_cpuid_entry2, entries);
 };
 
 /* for KVM_GET_PIT and KVM_SET_PIT */
@@ -398,7 +398,7 @@ struct kvm_xsave {
 	 * the contents of CPUID leaf 0xD on the host.
 	 */
 	__u32 region[1024];
-	__u32 extra[];
+	__DECLARE_FLEX_ARRAY(__u32, extra);
 };
 
 #define KVM_MAX_XCRS	16
@@ -566,7 +566,7 @@ struct kvm_pmu_event_filter {
 	__u32 fixed_counter_bitmap;
 	__u32 flags;
 	__u32 pad[4];
-	__u64 events[];
+	__DECLARE_FLEX_ARRAY(__u64, events);
 };
 
 #define KVM_PMU_EVENT_ALLOW 0

include/uapi/linux/kvm.h

@@ -11,6 +11,7 @@
 #include <linux/const.h>
 #include <linux/types.h>
 #include <linux/compiler.h>
+#include <linux/stddef.h>
 #include <linux/ioctl.h>
 #include <asm/kvm.h>
 
@@ -542,7 +543,7 @@ struct kvm_coalesced_mmio {
 
 struct kvm_coalesced_mmio_ring {
 	__u32 first, last;
-	struct kvm_coalesced_mmio coalesced_mmio[];
+	__DECLARE_FLEX_ARRAY(struct kvm_coalesced_mmio, coalesced_mmio);
 };
 
 #define KVM_COALESCED_MMIO_MAX \
@@ -592,7 +593,7 @@ struct kvm_clear_dirty_log {
 /* for KVM_SET_SIGNAL_MASK */
 struct kvm_signal_mask {
 	__u32 len;
-	__u8  sigset[];
+	__DECLARE_FLEX_ARRAY(__u8, sigset);
 };
 
 /* for KVM_TPR_ACCESS_REPORTING */
@@ -1051,7 +1052,7 @@ struct kvm_irq_routing_entry {
 struct kvm_irq_routing {
 	__u32 nr;
 	__u32 flags;
-	struct kvm_irq_routing_entry entries[];
+	__DECLARE_FLEX_ARRAY(struct kvm_irq_routing_entry, entries);
 };
 
 #define KVM_IRQFD_FLAG_DEASSIGN (1 << 0)
@@ -1142,7 +1143,7 @@ struct kvm_dirty_tlb {
 
 struct kvm_reg_list {
 	__u64 n; /* number of regs */
-	__u64 reg[];
+	__DECLARE_FLEX_ARRAY(__u64, reg);
 };
 
 struct kvm_one_reg {
@@ -1608,7 +1609,7 @@ struct kvm_stats_desc {
 #ifdef __KERNEL__
 	char name[KVM_STATS_NAME_SIZE];
 #else
-	char name[];
+	__DECLARE_FLEX_ARRAY(char, name);
 #endif
 };