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

Pull kvm fixes from Paolo Bonzini:
 "s390:

   - PCI interpretation compile fixes

  RISC-V:

   - fix unused variable warnings in vcpu_timer.c

   - move extern sbi_ext declarations to a header

  x86:

   - check validity of argument to KVM_SET_MP_STATE

   - use guest's global_ctrl to completely disable guest PEBS

   - fix a memory leak on memory allocation failure

   - mask off unsupported and unknown bits of IA32_ARCH_CAPABILITIES

   - fix build failure with Clang integrated assembler

   - fix MSR interception

   - always flush TLBs when enabling dirty logging"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86: check validity of argument to KVM_SET_MP_STATE
  perf/x86/core: Completely disable guest PEBS via guest's global_ctrl
  KVM: x86: fix memoryleak in kvm_arch_vcpu_create()
  KVM: x86: Mask off unsupported and unknown bits of IA32_ARCH_CAPABILITIES
  KVM: s390: pci: Hook to access KVM lowlevel from VFIO
  riscv: kvm: move extern sbi_ext declarations to a header
  riscv: kvm: vcpu_timer: fix unused variable warnings
  KVM: selftests: Fix ambiguous mov in KVM_ASM_SAFE()
  KVM: selftests: Fix KVM_EXCEPTION_MAGIC build with Clang
  KVM: VMX: Heed the 'msr' argument in msr_write_intercepted()
  kvm: x86: mmu: Always flush TLBs when enabling dirty logging
  kvm: x86: mmu: Drop the need_remote_flush() function

arch/riscv/include/asm/kvm_vcpu_sbi.h

@@ -33,4 +33,16 @@ void kvm_riscv_vcpu_sbi_system_reset(struct kvm_vcpu *vcpu,
 				     u32 type, u64 flags);
 const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(unsigned long extid);
 
+#ifdef CONFIG_RISCV_SBI_V01
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_v01;
+#endif
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_base;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_time;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_ipi;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_rfence;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_srst;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_experimental;
+extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_vendor;
+
 #endif /* __RISCV_KVM_VCPU_SBI_H__ */

arch/riscv/kvm/vcpu_sbi.c

@@ -32,23 +32,13 @@ static int kvm_linux_err_map_sbi(int err)
 	};
 }
 
-#ifdef CONFIG_RISCV_SBI_V01
-extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_v01;
-#else
+#ifndef CONFIG_RISCV_SBI_V01
 static const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_v01 = {
 	.extid_start = -1UL,
 	.extid_end = -1UL,
 	.handler = NULL,
 };
 #endif
-extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_base;
-extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_time;
-extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_ipi;
-extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_rfence;
-extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_srst;
-extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm;
-extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_experimental;
-extern const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_vendor;
 
 static const struct kvm_vcpu_sbi_extension *sbi_ext[] = {
 	&vcpu_sbi_ext_v01,

arch/riscv/kvm/vcpu_timer.c

@@ -299,7 +299,6 @@ static void kvm_riscv_vcpu_update_timedelta(struct kvm_vcpu *vcpu)
 
 void kvm_riscv_vcpu_timer_restore(struct kvm_vcpu *vcpu)
 {
-	struct kvm_vcpu_csr *csr;
 	struct kvm_vcpu_timer *t = &vcpu->arch.timer;
 
 	kvm_riscv_vcpu_update_timedelta(vcpu);
@@ -307,7 +306,6 @@ void kvm_riscv_vcpu_timer_restore(struct kvm_vcpu *vcpu)
 	if (!t->sstc_enabled)
 		return;
 
-	csr = &vcpu->arch.guest_csr;
 #if defined(CONFIG_32BIT)
 	csr_write(CSR_VSTIMECMP, (u32)t->next_cycles);
 	csr_write(CSR_VSTIMECMPH, (u32)(t->next_cycles >> 32));
@@ -324,13 +322,11 @@ void kvm_riscv_vcpu_timer_restore(struct kvm_vcpu *vcpu)
 
 void kvm_riscv_vcpu_timer_save(struct kvm_vcpu *vcpu)
 {
-	struct kvm_vcpu_csr *csr;
 	struct kvm_vcpu_timer *t = &vcpu->arch.timer;
 
 	if (!t->sstc_enabled)
 		return;
 
-	csr = &vcpu->arch.guest_csr;
 	t = &vcpu->arch.timer;
 #if defined(CONFIG_32BIT)
 	t->next_cycles = csr_read(CSR_VSTIMECMP);

arch/s390/include/asm/kvm_host.h

@@ -1038,16 +1038,11 @@ static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {}
 #define __KVM_HAVE_ARCH_VM_FREE
 void kvm_arch_free_vm(struct kvm *kvm);
 
-#ifdef CONFIG_VFIO_PCI_ZDEV_KVM
-int kvm_s390_pci_register_kvm(struct zpci_dev *zdev, struct kvm *kvm);
-void kvm_s390_pci_unregister_kvm(struct zpci_dev *zdev);
-#else
-static inline int kvm_s390_pci_register_kvm(struct zpci_dev *dev,
-					    struct kvm *kvm)
-{
-	return -EPERM;
-}
-static inline void kvm_s390_pci_unregister_kvm(struct zpci_dev *dev) {}
-#endif
+struct zpci_kvm_hook {
+	int (*kvm_register)(void *opaque, struct kvm *kvm);
+	void (*kvm_unregister)(void *opaque);
+};
+
+extern struct zpci_kvm_hook zpci_kvm_hook;
 
 #endif

arch/s390/kvm/pci.c

@@ -431,8 +431,9 @@ static void kvm_s390_pci_dev_release(struct zpci_dev *zdev)
  * available, enable them and let userspace indicate whether or not they will
  * be used (specify SHM bit to disable).
  */
-int kvm_s390_pci_register_kvm(struct zpci_dev *zdev, struct kvm *kvm)
+static int kvm_s390_pci_register_kvm(void *opaque, struct kvm *kvm)
 {
+	struct zpci_dev *zdev = opaque;
 	int rc;
 
 	if (!zdev)
@@ -510,10 +511,10 @@ int kvm_s390_pci_register_kvm(struct zpci_dev *zdev, struct kvm *kvm)
 	kvm_put_kvm(kvm);
 	return rc;
 }
-EXPORT_SYMBOL_GPL(kvm_s390_pci_register_kvm);
 
-void kvm_s390_pci_unregister_kvm(struct zpci_dev *zdev)
+static void kvm_s390_pci_unregister_kvm(void *opaque)
 {
+	struct zpci_dev *zdev = opaque;
 	struct kvm *kvm;
 
 	if (!zdev)
@@ -566,7 +567,6 @@ void kvm_s390_pci_unregister_kvm(struct zpci_dev *zdev)
 
 	kvm_put_kvm(kvm);
 }
-EXPORT_SYMBOL_GPL(kvm_s390_pci_unregister_kvm);
 
 void kvm_s390_pci_init_list(struct kvm *kvm)
 {
@@ -678,6 +678,8 @@ int kvm_s390_pci_init(void)
 
 	spin_lock_init(&aift->gait_lock);
 	mutex_init(&aift->aift_lock);
+	zpci_kvm_hook.kvm_register = kvm_s390_pci_register_kvm;
+	zpci_kvm_hook.kvm_unregister = kvm_s390_pci_unregister_kvm;
 
 	return 0;
 }
@@ -685,6 +687,8 @@ int kvm_s390_pci_init(void)
 void kvm_s390_pci_exit(void)
 {
 	mutex_destroy(&aift->aift_lock);
+	zpci_kvm_hook.kvm_register = NULL;
+	zpci_kvm_hook.kvm_unregister = NULL;
 
 	kfree(aift);
 }

arch/s390/pci/Makefile

@@ -5,5 +5,5 @@
 
 obj-$(CONFIG_PCI)	+= pci.o pci_irq.o pci_dma.o pci_clp.o pci_sysfs.o \
 			   pci_event.o pci_debug.o pci_insn.o pci_mmio.o \
-			   pci_bus.o
+			   pci_bus.o pci_kvm_hook.o
 obj-$(CONFIG_PCI_IOV)	+= pci_iov.o

arch/s390/pci/pci_kvm_hook.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VFIO ZPCI devices support
+ *
+ * Copyright (C) IBM Corp. 2022.  All rights reserved.
+ *	Author(s): Pierre Morel <pmorel@linux.ibm.com>
+ */
+#include <linux/kvm_host.h>
+
+struct zpci_kvm_hook zpci_kvm_hook;
+EXPORT_SYMBOL_GPL(zpci_kvm_hook);

arch/x86/events/intel/core.c

@@ -4052,8 +4052,9 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr, void *data)
 		/* Disable guest PEBS if host PEBS is enabled. */
 		arr[pebs_enable].guest = 0;
 	} else {
-		/* Disable guest PEBS for cross-mapped PEBS counters. */
+		/* Disable guest PEBS thoroughly for cross-mapped PEBS counters. */
 		arr[pebs_enable].guest &= ~kvm_pmu->host_cross_mapped_mask;
+		arr[global_ctrl].guest &= ~kvm_pmu->host_cross_mapped_mask;
 		/* Set hw GLOBAL_CTRL bits for PEBS counter when it runs for guest */
 		arr[global_ctrl].guest |= arr[pebs_enable].guest;
 	}

arch/x86/kvm/mmu/mmu.c

@@ -5361,19 +5361,6 @@ void kvm_mmu_free_obsolete_roots(struct kvm_vcpu *vcpu)
 	__kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.guest_mmu);
 }
 
-static bool need_remote_flush(u64 old, u64 new)
-{
-	if (!is_shadow_present_pte(old))
-		return false;
-	if (!is_shadow_present_pte(new))
-		return true;
-	if ((old ^ new) & SPTE_BASE_ADDR_MASK)
-		return true;
-	old ^= shadow_nx_mask;
-	new ^= shadow_nx_mask;
-	return (old & ~new & SPTE_PERM_MASK) != 0;
-}
-
 static u64 mmu_pte_write_fetch_gpte(struct kvm_vcpu *vcpu, gpa_t *gpa,
 				    int *bytes)
 {
@@ -5519,7 +5506,7 @@ static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
 			mmu_page_zap_pte(vcpu->kvm, sp, spte, NULL);
 			if (gentry && sp->role.level != PG_LEVEL_4K)
 				++vcpu->kvm->stat.mmu_pde_zapped;
-			if (need_remote_flush(entry, *spte))
+			if (is_shadow_present_pte(entry))
 				flush = true;
 			++spte;
 		}
@@ -6085,47 +6072,18 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm,
 				      const struct kvm_memory_slot *memslot,
 				      int start_level)
 {
-	bool flush = false;
-
 	if (kvm_memslots_have_rmaps(kvm)) {
 		write_lock(&kvm->mmu_lock);
-		flush = slot_handle_level(kvm, memslot, slot_rmap_write_protect,
-					  start_level, KVM_MAX_HUGEPAGE_LEVEL,
-					  false);
+		slot_handle_level(kvm, memslot, slot_rmap_write_protect,
+				  start_level, KVM_MAX_HUGEPAGE_LEVEL, false);
 		write_unlock(&kvm->mmu_lock);
 	}
 
 	if (is_tdp_mmu_enabled(kvm)) {
 		read_lock(&kvm->mmu_lock);
-		flush |= kvm_tdp_mmu_wrprot_slot(kvm, memslot, start_level);
+		kvm_tdp_mmu_wrprot_slot(kvm, memslot, start_level);
 		read_unlock(&kvm->mmu_lock);
 	}
-
-	/*
-	 * Flush TLBs if any SPTEs had to be write-protected to ensure that
-	 * guest writes are reflected in the dirty bitmap before the memslot
-	 * update completes, i.e. before enabling dirty logging is visible to
-	 * userspace.
-	 *
-	 * Perform the TLB flush outside the mmu_lock to reduce the amount of
-	 * time the lock is held. However, this does mean that another CPU can
-	 * now grab mmu_lock and encounter a write-protected SPTE while CPUs
-	 * still have a writable mapping for the associated GFN in their TLB.
-	 *
-	 * This is safe but requires KVM to be careful when making decisions
-	 * based on the write-protection status of an SPTE. Specifically, KVM
-	 * also write-protects SPTEs to monitor changes to guest page tables
-	 * during shadow paging, and must guarantee no CPUs can write to those
-	 * page before the lock is dropped. As mentioned in the previous
-	 * paragraph, a write-protected SPTE is no guarantee that CPU cannot
-	 * perform writes. So to determine if a TLB flush is truly required, KVM
-	 * will clear a separate software-only bit (MMU-writable) and skip the
-	 * flush if-and-only-if this bit was already clear.
-	 *
-	 * See is_writable_pte() for more details.
-	 */
-	if (flush)
-		kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
 }
 
 static inline bool need_topup(struct kvm_mmu_memory_cache *cache, int min)
@@ -6493,32 +6451,30 @@ void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm,
 void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm,
 				   const struct kvm_memory_slot *memslot)
 {
-	bool flush = false;
-
 	if (kvm_memslots_have_rmaps(kvm)) {
 		write_lock(&kvm->mmu_lock);
 		/*
 		 * Clear dirty bits only on 4k SPTEs since the legacy MMU only
 		 * support dirty logging at a 4k granularity.
 		 */
-		flush = slot_handle_level_4k(kvm, memslot, __rmap_clear_dirty, false);
+		slot_handle_level_4k(kvm, memslot, __rmap_clear_dirty, false);
 		write_unlock(&kvm->mmu_lock);
 	}
 
 	if (is_tdp_mmu_enabled(kvm)) {
 		read_lock(&kvm->mmu_lock);
-		flush |= kvm_tdp_mmu_clear_dirty_slot(kvm, memslot);
+		kvm_tdp_mmu_clear_dirty_slot(kvm, memslot);
 		read_unlock(&kvm->mmu_lock);
 	}
 
 	/*
+	 * The caller will flush the TLBs after this function returns.
+	 *
 	 * It's also safe to flush TLBs out of mmu lock here as currently this
 	 * function is only used for dirty logging, in which case flushing TLB
 	 * out of mmu lock also guarantees no dirty pages will be lost in
 	 * dirty_bitmap.
 	 */
-	if (flush)
-		kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
 }
 
 void kvm_mmu_zap_all(struct kvm *kvm)

arch/x86/kvm/mmu/spte.h

@@ -343,7 +343,7 @@ static __always_inline bool is_rsvd_spte(struct rsvd_bits_validate *rsvd_check,
 }
 
 /*
- * An shadow-present leaf SPTE may be non-writable for 3 possible reasons:
+ * A shadow-present leaf SPTE may be non-writable for 4 possible reasons:
  *
  *  1. To intercept writes for dirty logging. KVM write-protects huge pages
  *     so that they can be split be split down into the dirty logging
@@ -361,8 +361,13 @@ static __always_inline bool is_rsvd_spte(struct rsvd_bits_validate *rsvd_check,
  *     read-only memslot or guest memory backed by a read-only VMA. Writes to
  *     such pages are disallowed entirely.
  *
- * To keep track of why a given SPTE is write-protected, KVM uses 2
- * software-only bits in the SPTE:
+ *  4. To emulate the Accessed bit for SPTEs without A/D bits.  Note, in this
+ *     case, the SPTE is access-protected, not just write-protected!
+ *
+ * For cases #1 and #4, KVM can safely make such SPTEs writable without taking
+ * mmu_lock as capturing the Accessed/Dirty state doesn't require taking it.
+ * To differentiate #1 and #4 from #2 and #3, KVM uses two software-only bits
+ * in the SPTE:
  *
  *  shadow_mmu_writable_mask, aka MMU-writable -
  *    Cleared on SPTEs that KVM is currently write-protecting for shadow paging
@@ -391,7 +396,8 @@ static __always_inline bool is_rsvd_spte(struct rsvd_bits_validate *rsvd_check,
  * shadow page tables between vCPUs. Write-protecting an SPTE for dirty logging
  * (which does not clear the MMU-writable bit), does not flush TLBs before
  * dropping the lock, as it only needs to synchronize guest writes with the
- * dirty bitmap.
+ * dirty bitmap. Similarly, making the SPTE inaccessible (and non-writable) for
+ * access-tracking via the clear_young() MMU notifier also does not flush TLBs.
  *
  * So, there is the problem: clearing the MMU-writable bit can encounter a
  * write-protected SPTE while CPUs still have writable mappings for that SPTE

arch/x86/kvm/vmx/vmx.c

@@ -843,8 +843,7 @@ static bool msr_write_intercepted(struct vcpu_vmx *vmx, u32 msr)
 	if (!(exec_controls_get(vmx) & CPU_BASED_USE_MSR_BITMAPS))
 		return true;
 
-	return vmx_test_msr_bitmap_write(vmx->loaded_vmcs->msr_bitmap,
-					 MSR_IA32_SPEC_CTRL);
+	return vmx_test_msr_bitmap_write(vmx->loaded_vmcs->msr_bitmap, msr);
 }
 
 unsigned int __vmx_vcpu_run_flags(struct vcpu_vmx *vmx)

arch/x86/kvm/x86.c

@@ -1557,12 +1557,32 @@ static const u32 msr_based_features_all[] = {
 static u32 msr_based_features[ARRAY_SIZE(msr_based_features_all)];
 static unsigned int num_msr_based_features;
 
+/*
+ * Some IA32_ARCH_CAPABILITIES bits have dependencies on MSRs that KVM
+ * does not yet virtualize. These include:
+ *   10 - MISC_PACKAGE_CTRLS
+ *   11 - ENERGY_FILTERING_CTL
+ *   12 - DOITM
+ *   18 - FB_CLEAR_CTRL
+ *   21 - XAPIC_DISABLE_STATUS
+ *   23 - OVERCLOCKING_STATUS
+ */
+
+#define KVM_SUPPORTED_ARCH_CAP \
+	(ARCH_CAP_RDCL_NO | ARCH_CAP_IBRS_ALL | ARCH_CAP_RSBA | \
+	 ARCH_CAP_SKIP_VMENTRY_L1DFLUSH | ARCH_CAP_SSB_NO | ARCH_CAP_MDS_NO | \
+	 ARCH_CAP_PSCHANGE_MC_NO | ARCH_CAP_TSX_CTRL_MSR | ARCH_CAP_TAA_NO | \
+	 ARCH_CAP_SBDR_SSDP_NO | ARCH_CAP_FBSDP_NO | ARCH_CAP_PSDP_NO | \
+	 ARCH_CAP_FB_CLEAR | ARCH_CAP_RRSBA | ARCH_CAP_PBRSB_NO)
+
 static u64 kvm_get_arch_capabilities(void)
 {
 	u64 data = 0;
 
-	if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES))
+	if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES)) {
 		rdmsrl(MSR_IA32_ARCH_CAPABILITIES, data);
+		data &= KVM_SUPPORTED_ARCH_CAP;
+	}
 
 	/*
 	 * If nx_huge_pages is enabled, KVM's shadow paging will ensure that
@@ -1610,9 +1630,6 @@ static u64 kvm_get_arch_capabilities(void)
 		 */
 	}
 
-	/* Guests don't need to know "Fill buffer clear control" exists */
-	data &= ~ARCH_CAP_FB_CLEAR_CTRL;
-
 	return data;
 }
 
@@ -10652,7 +10669,8 @@ static inline int vcpu_block(struct kvm_vcpu *vcpu)
 	case KVM_MP_STATE_INIT_RECEIVED:
 		break;
 	default:
-		return -EINTR;
+		WARN_ON_ONCE(1);
+		break;
 	}
 	return 1;
 }
@@ -11093,9 +11111,22 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
 
 	vcpu_load(vcpu);
 
-	if (!lapic_in_kernel(vcpu) &&
-	    mp_state->mp_state != KVM_MP_STATE_RUNNABLE)
+	switch (mp_state->mp_state) {
+	case KVM_MP_STATE_UNINITIALIZED:
+	case KVM_MP_STATE_HALTED:
+	case KVM_MP_STATE_AP_RESET_HOLD:
+	case KVM_MP_STATE_INIT_RECEIVED:
+	case KVM_MP_STATE_SIPI_RECEIVED:
+		if (!lapic_in_kernel(vcpu))
+			goto out;
+		break;
+
+	case KVM_MP_STATE_RUNNABLE:
+		break;
+
+	default:
 		goto out;
+	}
 
 	/*
 	 * KVM_MP_STATE_INIT_RECEIVED means the processor is in
@@ -11563,7 +11594,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 	vcpu->arch.mci_ctl2_banks = kcalloc(KVM_MAX_MCE_BANKS, sizeof(u64),
 					    GFP_KERNEL_ACCOUNT);
 	if (!vcpu->arch.mce_banks || !vcpu->arch.mci_ctl2_banks)
-		goto fail_free_pio_data;
+		goto fail_free_mce_banks;
 	vcpu->arch.mcg_cap = KVM_MAX_MCE_BANKS;
 
 	if (!zalloc_cpumask_var(&vcpu->arch.wbinvd_dirty_mask,
@@ -11617,7 +11648,6 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 fail_free_mce_banks:
 	kfree(vcpu->arch.mce_banks);
 	kfree(vcpu->arch.mci_ctl2_banks);
-fail_free_pio_data:
 	free_page((unsigned long)vcpu->arch.pio_data);
 fail_free_lapic:
 	kvm_free_lapic(vcpu);
@@ -12473,6 +12503,50 @@ static void kvm_mmu_slot_apply_flags(struct kvm *kvm,
 		} else {
 			kvm_mmu_slot_remove_write_access(kvm, new, PG_LEVEL_4K);
 		}
+
+		/*
+		 * Unconditionally flush the TLBs after enabling dirty logging.
+		 * A flush is almost always going to be necessary (see below),
+		 * and unconditionally flushing allows the helpers to omit
+		 * the subtly complex checks when removing write access.
+		 *
+		 * Do the flush outside of mmu_lock to reduce the amount of
+		 * time mmu_lock is held.  Flushing after dropping mmu_lock is
+		 * safe as KVM only needs to guarantee the slot is fully
+		 * write-protected before returning to userspace, i.e. before
+		 * userspace can consume the dirty status.
+		 *
+		 * Flushing outside of mmu_lock requires KVM to be careful when
+		 * making decisions based on writable status of an SPTE, e.g. a
+		 * !writable SPTE doesn't guarantee a CPU can't perform writes.
+		 *
+		 * Specifically, KVM also write-protects guest page tables to
+		 * monitor changes when using shadow paging, and must guarantee
+		 * no CPUs can write to those page before mmu_lock is dropped.
+		 * Because CPUs may have stale TLB entries at this point, a
+		 * !writable SPTE doesn't guarantee CPUs can't perform writes.
+		 *
+		 * KVM also allows making SPTES writable outside of mmu_lock,
+		 * e.g. to allow dirty logging without taking mmu_lock.
+		 *
+		 * To handle these scenarios, KVM uses a separate software-only
+		 * bit (MMU-writable) to track if a SPTE is !writable due to
+		 * a guest page table being write-protected (KVM clears the
+		 * MMU-writable flag when write-protecting for shadow paging).
+		 *
+		 * The use of MMU-writable is also the primary motivation for
+		 * the unconditional flush.  Because KVM must guarantee that a
+		 * CPU doesn't contain stale, writable TLB entries for a
+		 * !MMU-writable SPTE, KVM must flush if it encounters any
+		 * MMU-writable SPTE regardless of whether the actual hardware
+		 * writable bit was set.  I.e. KVM is almost guaranteed to need
+		 * to flush, while unconditionally flushing allows the "remove
+		 * write access" helpers to ignore MMU-writable entirely.
+		 *
+		 * See is_writable_pte() for more details (the case involving
+		 * access-tracked SPTEs is particularly relevant).
+		 */
+		kvm_arch_flush_remote_tlbs_memslot(kvm, new);
 	}
 }
 

drivers/vfio/pci/vfio_pci_zdev.c

@@ -151,7 +151,10 @@ int vfio_pci_zdev_open_device(struct vfio_pci_core_device *vdev)
 	if (!vdev->vdev.kvm)
 		return 0;
 
-	return kvm_s390_pci_register_kvm(zdev, vdev->vdev.kvm);
+	if (zpci_kvm_hook.kvm_register)
+		return zpci_kvm_hook.kvm_register(zdev, vdev->vdev.kvm);
+
+	return -ENOENT;
 }
 
 void vfio_pci_zdev_close_device(struct vfio_pci_core_device *vdev)
@@ -161,5 +164,6 @@ void vfio_pci_zdev_close_device(struct vfio_pci_core_device *vdev)
 	if (!zdev || !vdev->vdev.kvm)
 		return;
 
-	kvm_s390_pci_unregister_kvm(zdev);
+	if (zpci_kvm_hook.kvm_unregister)
+		zpci_kvm_hook.kvm_unregister(zdev);
 }

tools/testing/selftests/kvm/include/x86_64/processor.h

@@ -754,7 +754,7 @@ void vm_install_exception_handler(struct kvm_vm *vm, int vector,
 			void (*handler)(struct ex_regs *));
 
 /* If a toddler were to say "abracadabra". */
-#define KVM_EXCEPTION_MAGIC 0xabacadabaull
+#define KVM_EXCEPTION_MAGIC 0xabacadabaULL
 
 /*
  * KVM selftest exception fixup uses registers to coordinate with the exception
@@ -786,7 +786,7 @@ void vm_install_exception_handler(struct kvm_vm *vm, int vector,
 	"lea 1f(%%rip), %%r10\n\t"				\
 	"lea 2f(%%rip), %%r11\n\t"				\
 	"1: " insn "\n\t"					\
-	"mov $0, %[vector]\n\t"					\
+	"movb $0, %[vector]\n\t"				\
 	"jmp 3f\n\t"						\
 	"2:\n\t"						\
 	"mov  %%r9b, %[vector]\n\t"				\