Merge tag 'kvmarm-fixes-for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into kvm-master

KVM/ARM fixes for 5.1

- Fix THP handling in the presence of pre-existing PTEs
- Honor request for PTE mappings even when THPs are available
- GICv4 performance improvement
- Take the srcu lock when writing to guest-controlled ITS data structures
- Reset the virtual PMU in preemptible context
- Various cleanups

Author: bonzini

arch/arm/include/asm/kvm_mmu.h

@@ -381,6 +381,17 @@ static inline int kvm_read_guest_lock(struct kvm *kvm,
 	return ret;
 }
 
+static inline int kvm_write_guest_lock(struct kvm *kvm, gpa_t gpa,
+				       const void *data, unsigned long len)
+{
+	int srcu_idx = srcu_read_lock(&kvm->srcu);
+	int ret = kvm_write_guest(kvm, gpa, data, len);
+
+	srcu_read_unlock(&kvm->srcu, srcu_idx);
+
+	return ret;
+}
+
 static inline void *kvm_get_hyp_vector(void)
 {
 	switch(read_cpuid_part()) {

arch/arm/include/asm/stage2_pgtable.h

@@ -75,6 +75,8 @@ static inline bool kvm_stage2_has_pud(struct kvm *kvm)
 
 #define S2_PMD_MASK				PMD_MASK
 #define S2_PMD_SIZE				PMD_SIZE
+#define S2_PUD_MASK				PUD_MASK
+#define S2_PUD_SIZE				PUD_SIZE
 
 static inline bool kvm_stage2_has_pmd(struct kvm *kvm)
 {

arch/arm64/include/asm/kvm_mmu.h

@@ -445,6 +445,17 @@ static inline int kvm_read_guest_lock(struct kvm *kvm,
 	return ret;
 }
 
+static inline int kvm_write_guest_lock(struct kvm *kvm, gpa_t gpa,
+				       const void *data, unsigned long len)
+{
+	int srcu_idx = srcu_read_lock(&kvm->srcu);
+	int ret = kvm_write_guest(kvm, gpa, data, len);
+
+	srcu_read_unlock(&kvm->srcu, srcu_idx);
+
+	return ret;
+}
+
 #ifdef CONFIG_KVM_INDIRECT_VECTORS
 /*
  * EL2 vectors can be mapped and rerouted in a number of ways,

arch/arm64/kvm/reset.c

@@ -123,6 +123,9 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 	int ret = -EINVAL;
 	bool loaded;
 
+	/* Reset PMU outside of the non-preemptible section */
+	kvm_pmu_vcpu_reset(vcpu);
+
 	preempt_disable();
 	loaded = (vcpu->cpu != -1);
 	if (loaded)
@@ -170,9 +173,6 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
 		vcpu->arch.reset_state.reset = false;
 	}
 
-	/* Reset PMU */
-	kvm_pmu_vcpu_reset(vcpu);
-
 	/* Default workaround setup is enabled (if supported) */
 	if (kvm_arm_have_ssbd() == KVM_SSBD_KERNEL)
 		vcpu->arch.workaround_flags |= VCPU_WORKAROUND_2_FLAG;

virt/kvm/arm/hyp/vgic-v3-sr.c

@@ -222,7 +222,7 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
 		}
 	}
 
-	if (used_lrs) {
+	if (used_lrs || cpu_if->its_vpe.its_vm) {
 		int i;
 		u32 elrsr;
 
@@ -247,7 +247,7 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)
 	u64 used_lrs = vcpu->arch.vgic_cpu.used_lrs;
 	int i;
 
-	if (used_lrs) {
+	if (used_lrs || cpu_if->its_vpe.its_vm) {
 		write_gicreg(cpu_if->vgic_hcr, ICH_HCR_EL2);
 
 		for (i = 0; i < used_lrs; i++)

virt/kvm/arm/mmu.c

@@ -102,8 +102,7 @@ static bool kvm_is_device_pfn(unsigned long pfn)
  * @addr:	IPA
  * @pmd:	pmd pointer for IPA
  *
- * Function clears a PMD entry, flushes addr 1st and 2nd stage TLBs. Marks all
- * pages in the range dirty.
+ * Function clears a PMD entry, flushes addr 1st and 2nd stage TLBs.
  */
 static void stage2_dissolve_pmd(struct kvm *kvm, phys_addr_t addr, pmd_t *pmd)
 {
@@ -121,8 +120,7 @@ static void stage2_dissolve_pmd(struct kvm *kvm, phys_addr_t addr, pmd_t *pmd)
  * @addr:	IPA
  * @pud:	pud pointer for IPA
  *
- * Function clears a PUD entry, flushes addr 1st and 2nd stage TLBs. Marks all
- * pages in the range dirty.
+ * Function clears a PUD entry, flushes addr 1st and 2nd stage TLBs.
  */
 static void stage2_dissolve_pud(struct kvm *kvm, phys_addr_t addr, pud_t *pudp)
 {
@@ -899,9 +897,8 @@ int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size,
  * kvm_alloc_stage2_pgd - allocate level-1 table for stage-2 translation.
  * @kvm:	The KVM struct pointer for the VM.
  *
- * Allocates only the stage-2 HW PGD level table(s) (can support either full
- * 40-bit input addresses or limited to 32-bit input addresses). Clears the
- * allocated pages.
+ * Allocates only the stage-2 HW PGD level table(s) of size defined by
+ * stage2_pgd_size(kvm).
  *
  * Note we don't need locking here as this is only called when the VM is
  * created, which can only be done once.
@@ -1067,25 +1064,43 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache
 {
 	pmd_t *pmd, old_pmd;
 
+retry:
 	pmd = stage2_get_pmd(kvm, cache, addr);
 	VM_BUG_ON(!pmd);
 
 	old_pmd = *pmd;
+	/*
+	 * Multiple vcpus faulting on the same PMD entry, can
+	 * lead to them sequentially updating the PMD with the
+	 * same value. Following the break-before-make
+	 * (pmd_clear() followed by tlb_flush()) process can
+	 * hinder forward progress due to refaults generated
+	 * on missing translations.
+	 *
+	 * Skip updating the page table if the entry is
+	 * unchanged.
+	 */
+	if (pmd_val(old_pmd) == pmd_val(*new_pmd))
+		return 0;
+
 	if (pmd_present(old_pmd)) {
 		/*
-		 * Multiple vcpus faulting on the same PMD entry, can
-		 * lead to them sequentially updating the PMD with the
-		 * same value. Following the break-before-make
-		 * (pmd_clear() followed by tlb_flush()) process can
-		 * hinder forward progress due to refaults generated
-		 * on missing translations.
+		 * If we already have PTE level mapping for this block,
+		 * we must unmap it to avoid inconsistent TLB state and
+		 * leaking the table page. We could end up in this situation
+		 * if the memory slot was marked for dirty logging and was
+		 * reverted, leaving PTE level mappings for the pages accessed
+		 * during the period. So, unmap the PTE level mapping for this
+		 * block and retry, as we could have released the upper level
+		 * table in the process.
 		 *
-		 * Skip updating the page table if the entry is
-		 * unchanged.
+		 * Normal THP split/merge follows mmu_notifier callbacks and do
+		 * get handled accordingly.
 		 */
-		if (pmd_val(old_pmd) == pmd_val(*new_pmd))
-			return 0;
-
+		if (!pmd_thp_or_huge(old_pmd)) {
+			unmap_stage2_range(kvm, addr & S2_PMD_MASK, S2_PMD_SIZE);
+			goto retry;
+		}
 		/*
 		 * Mapping in huge pages should only happen through a
 		 * fault.  If a page is merged into a transparent huge
@@ -1097,8 +1112,7 @@ static int stage2_set_pmd_huge(struct kvm *kvm, struct kvm_mmu_memory_cache
 		 * should become splitting first, unmapped, merged,
 		 * and mapped back in on-demand.
 		 */
-		VM_BUG_ON(pmd_pfn(old_pmd) != pmd_pfn(*new_pmd));
-
+		WARN_ON_ONCE(pmd_pfn(old_pmd) != pmd_pfn(*new_pmd));
 		pmd_clear(pmd);
 		kvm_tlb_flush_vmid_ipa(kvm, addr);
 	} else {
@@ -1114,21 +1128,31 @@ static int stage2_set_pud_huge(struct kvm *kvm, struct kvm_mmu_memory_cache *cac
 {
 	pud_t *pudp, old_pud;
 
+retry:
 	pudp = stage2_get_pud(kvm, cache, addr);
 	VM_BUG_ON(!pudp);
 
 	old_pud = *pudp;
 
 	/*
 	 * A large number of vcpus faulting on the same stage 2 entry,
-	 * can lead to a refault due to the
-	 * stage2_pud_clear()/tlb_flush(). Skip updating the page
-	 * tables if there is no change.
+	 * can lead to a refault due to the stage2_pud_clear()/tlb_flush().
+	 * Skip updating the page tables if there is no change.
 	 */
 	if (pud_val(old_pud) == pud_val(*new_pudp))
 		return 0;
 
 	if (stage2_pud_present(kvm, old_pud)) {
+		/*
+		 * If we already have table level mapping for this block, unmap
+		 * the range for this block and retry.
+		 */
+		if (!stage2_pud_huge(kvm, old_pud)) {
+			unmap_stage2_range(kvm, addr & S2_PUD_MASK, S2_PUD_SIZE);
+			goto retry;
+		}
+
+		WARN_ON_ONCE(kvm_pud_pfn(old_pud) != kvm_pud_pfn(*new_pudp));
 		stage2_pud_clear(kvm, pudp);
 		kvm_tlb_flush_vmid_ipa(kvm, addr);
 	} else {
@@ -1451,13 +1475,11 @@ static void stage2_wp_pmds(struct kvm *kvm, pud_t *pud,
 }
 
 /**
-  * stage2_wp_puds - write protect PGD range
-  * @pgd:	pointer to pgd entry
-  * @addr:	range start address
-  * @end:	range end address
-  *
-  * Process PUD entries, for a huge PUD we cause a panic.
-  */
+ * stage2_wp_puds - write protect PGD range
+ * @pgd:	pointer to pgd entry
+ * @addr:	range start address
+ * @end:	range end address
+ */
 static void  stage2_wp_puds(struct kvm *kvm, pgd_t *pgd,
 			    phys_addr_t addr, phys_addr_t end)
 {
@@ -1594,8 +1616,9 @@ static void kvm_send_hwpoison_signal(unsigned long address,
 	send_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb, current);
 }
 
-static bool fault_supports_stage2_pmd_mappings(struct kvm_memory_slot *memslot,
-					       unsigned long hva)
+static bool fault_supports_stage2_huge_mapping(struct kvm_memory_slot *memslot,
+					       unsigned long hva,
+					       unsigned long map_size)
 {
 	gpa_t gpa_start;
 	hva_t uaddr_start, uaddr_end;
@@ -1610,34 +1633,34 @@ static bool fault_supports_stage2_pmd_mappings(struct kvm_memory_slot *memslot,
 
 	/*
 	 * Pages belonging to memslots that don't have the same alignment
-	 * within a PMD for userspace and IPA cannot be mapped with stage-2
-	 * PMD entries, because we'll end up mapping the wrong pages.
+	 * within a PMD/PUD for userspace and IPA cannot be mapped with stage-2
+	 * PMD/PUD entries, because we'll end up mapping the wrong pages.
 	 *
 	 * Consider a layout like the following:
 	 *
 	 *    memslot->userspace_addr:
 	 *    +-----+--------------------+--------------------+---+
-	 *    |abcde|fgh  Stage-1 PMD    |    Stage-1 PMD   tv|xyz|
+	 *    |abcde|fgh  Stage-1 block  |    Stage-1 block tv|xyz|
 	 *    +-----+--------------------+--------------------+---+
 	 *
 	 *    memslot->base_gfn << PAGE_SIZE:
 	 *      +---+--------------------+--------------------+-----+
-	 *      |abc|def  Stage-2 PMD    |    Stage-2 PMD     |tvxyz|
+	 *      |abc|def  Stage-2 block  |    Stage-2 block   |tvxyz|
 	 *      +---+--------------------+--------------------+-----+
 	 *
-	 * If we create those stage-2 PMDs, we'll end up with this incorrect
+	 * If we create those stage-2 blocks, we'll end up with this incorrect
 	 * mapping:
 	 *   d -> f
 	 *   e -> g
 	 *   f -> h
 	 */
-	if ((gpa_start & ~S2_PMD_MASK) != (uaddr_start & ~S2_PMD_MASK))
+	if ((gpa_start & (map_size - 1)) != (uaddr_start & (map_size - 1)))
 		return false;
 
 	/*
 	 * Next, let's make sure we're not trying to map anything not covered
-	 * by the memslot. This means we have to prohibit PMD size mappings
-	 * for the beginning and end of a non-PMD aligned and non-PMD sized
+	 * by the memslot. This means we have to prohibit block size mappings
+	 * for the beginning and end of a non-block aligned and non-block sized
 	 * memory slot (illustrated by the head and tail parts of the
 	 * userspace view above containing pages 'abcde' and 'xyz',
 	 * respectively).
@@ -1646,8 +1669,8 @@ static bool fault_supports_stage2_pmd_mappings(struct kvm_memory_slot *memslot,
 	 * userspace_addr or the base_gfn, as both are equally aligned (per
 	 * the check above) and equally sized.
 	 */
-	return (hva & S2_PMD_MASK) >= uaddr_start &&
-	       (hva & S2_PMD_MASK) + S2_PMD_SIZE <= uaddr_end;
+	return (hva & ~(map_size - 1)) >= uaddr_start &&
+	       (hva & ~(map_size - 1)) + map_size <= uaddr_end;
 }
 
 static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
@@ -1676,12 +1699,6 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 		return -EFAULT;
 	}
 
-	if (!fault_supports_stage2_pmd_mappings(memslot, hva))
-		force_pte = true;
-
-	if (logging_active)
-		force_pte = true;
-
 	/* Let's check if we will get back a huge page backed by hugetlbfs */
 	down_read(&current->mm->mmap_sem);
 	vma = find_vma_intersection(current->mm, hva, hva + 1);
@@ -1692,18 +1709,22 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	}
 
 	vma_pagesize = vma_kernel_pagesize(vma);
+	if (logging_active ||
+	    !fault_supports_stage2_huge_mapping(memslot, hva, vma_pagesize)) {
+		force_pte = true;
+		vma_pagesize = PAGE_SIZE;
+	}
+
 	/*
 	 * The stage2 has a minimum of 2 level table (For arm64 see
 	 * kvm_arm_setup_stage2()). Hence, we are guaranteed that we can
 	 * use PMD_SIZE huge mappings (even when the PMD is folded into PGD).
 	 * As for PUD huge maps, we must make sure that we have at least
 	 * 3 levels, i.e, PMD is not folded.
 	 */
-	if ((vma_pagesize == PMD_SIZE ||
-	     (vma_pagesize == PUD_SIZE && kvm_stage2_has_pmd(kvm))) &&
-	    !force_pte) {
+	if (vma_pagesize == PMD_SIZE ||
+	    (vma_pagesize == PUD_SIZE && kvm_stage2_has_pmd(kvm)))
 		gfn = (fault_ipa & huge_page_mask(hstate_vma(vma))) >> PAGE_SHIFT;
-	}
 	up_read(&current->mm->mmap_sem);
 
 	/* We need minimum second+third level pages */