[PATCH v3 37/66] KVM: arm64: nv: Unmap/flush shadow stage 2 page tables

Marc Zyngier
2020-12-10T16:32:57Z

From: Christoffer Dall <christoffer.dall@linaro.org>

Unmap/flush shadow stage 2 page tables for the nested VMs as well as the
stage 2 page table for the guest hypervisor.

Note: A bunch of the code in mmu.c relating to MMU notifiers is
currently dealt with in an extremely abrupt way, for example by clearing
out an entire shadow stage-2 table. This will be handled in a more
efficient way using the reverse mapping feature in a later version of
the patch series.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Jintack Lim <jintack.lim@linaro.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/include/asm/kvm_mmu.h | 3 +++
arch/arm64/include/asm/kvm_nested.h | 3 +++
arch/arm64/kvm/mmu.c | 34 ++++++++++++++++++++++---
arch/arm64/kvm/nested.c | 39 +++++++++++++++++++++++++++++
4 files changed, 75 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index ec39015bb2a6..e2c58ad46bd1 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -183,6 +183,8 @@ int create_hyp_io_mappings(phys_addr_t phys_addr, size_t size,
void __iomem **haddr);
int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size,
void **haddr);
+void kvm_stage2_flush_range(struct kvm_s2_mmu *mmu,
+ phys_addr_t addr, phys_addr_t end);
void free_hyp_pgds(void);

void kvm_unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 size);
@@ -191,6 +193,7 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu);
void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu);
int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
phys_addr_t pa, unsigned long size, bool writable);
+void kvm_stage2_wp_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end);

int kvm_handle_guest_abort(struct kvm_vcpu *vcpu);

diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
index 3f3d8e10bd99..2987806850f0 100644
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -114,6 +114,9 @@ extern int kvm_walk_nested_s2(struct kvm_vcpu *vcpu, phys_addr_t gipa,
extern int kvm_s2_handle_perm_fault(struct kvm_vcpu *vcpu,
struct kvm_s2_trans *trans);
extern int kvm_inject_s2_fault(struct kvm_vcpu *vcpu, u64 esr_el2);
+extern void kvm_nested_s2_wp(struct kvm *kvm);
+extern void kvm_nested_s2_clear(struct kvm *kvm);
+extern void kvm_nested_s2_flush(struct kvm *kvm);
int handle_wfx_nested(struct kvm_vcpu *vcpu, bool is_wfe);
extern bool __forward_traps(struct kvm_vcpu *vcpu, unsigned int reg,
u64 control_bit);
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 6f973efb2cc3..36cb9fa22153 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -141,13 +141,20 @@ void kvm_unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64 size)
__unmap_stage2_range(mmu, start, size, true);
}

+void kvm_stage2_flush_range(struct kvm_s2_mmu *mmu,
+ phys_addr_t addr, phys_addr_t end)
+{
+ stage2_apply_range_resched(mmu->kvm, addr, end, kvm_pgtable_stage2_flush);
+}
+
static void stage2_flush_memslot(struct kvm *kvm,
struct kvm_memory_slot *memslot)
{
phys_addr_t addr = memslot->base_gfn << PAGE_SHIFT;
phys_addr_t end = addr + PAGE_SIZE * memslot->npages;
+ struct kvm_s2_mmu *mmu = &kvm->arch.mmu;

- stage2_apply_range_resched(kvm, addr, end, kvm_pgtable_stage2_flush);
+ kvm_stage2_flush_range(mmu, addr, end);
}

/**
@@ -170,6 +177,8 @@ static void stage2_flush_vm(struct kvm *kvm)
kvm_for_each_memslot(memslot, slots)
stage2_flush_memslot(kvm, memslot);

+ kvm_nested_s2_flush(kvm);
+
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);
}
@@ -465,6 +474,8 @@ void stage2_unmap_vm(struct kvm *kvm)
kvm_for_each_memslot(memslot, slots)
stage2_unmap_memslot(kvm, memslot);

+ kvm_nested_s2_clear(kvm);
+
spin_unlock(&kvm->mmu_lock);
mmap_read_unlock(current->mm);
srcu_read_unlock(&kvm->srcu, idx);
@@ -539,7 +550,7 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
* @addr: Start address of range
* @end: End address of range
*/
-static void stage2_wp_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end)
+void kvm_stage2_wp_range(struct kvm_s2_mmu *mmu, phys_addr_t addr, phys_addr_t end)
{
struct kvm *kvm = mmu->kvm;
stage2_apply_range_resched(kvm, addr, end, kvm_pgtable_stage2_wrprotect);
@@ -571,7 +582,8 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot)
end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;

spin_lock(&kvm->mmu_lock);
- stage2_wp_range(&kvm->arch.mmu, start, end);
+ kvm_stage2_wp_range(&kvm->arch.mmu, start, end);
+ kvm_nested_s2_wp(kvm);
spin_unlock(&kvm->mmu_lock);
kvm_flush_remote_tlbs(kvm);
}
@@ -595,7 +607,7 @@ static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm,
phys_addr_t start = (base_gfn + __ffs(mask)) << PAGE_SHIFT;
phys_addr_t end = (base_gfn + __fls(mask) + 1) << PAGE_SHIFT;

- stage2_wp_range(&kvm->arch.mmu, start, end);
+ kvm_stage2_wp_range(&kvm->arch.mmu, start, end);
}

/*
@@ -610,6 +622,7 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
gfn_t gfn_offset, unsigned long mask)
{
kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask);
+ kvm_nested_s2_wp(kvm);
}

static void clean_dcache_guest_page(kvm_pfn_t pfn, unsigned long size)
@@ -1164,6 +1177,7 @@ static int kvm_unmap_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *dat
bool may_block = flags & MMU_NOTIFIER_RANGE_BLOCKABLE;

__unmap_stage2_range(&kvm->arch.mmu, gpa, size, may_block);
+ kvm_nested_s2_clear(kvm);
return 0;
}

@@ -1192,6 +1206,7 @@ static int kvm_set_spte_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data
*/
kvm_pgtable_stage2_map(kvm->arch.mmu.pgt, gpa, PAGE_SIZE,
__pfn_to_phys(*pfn), KVM_PGTABLE_PROT_R, NULL);
+ kvm_nested_s2_clear(kvm);
return 0;
}

@@ -1223,12 +1238,22 @@ static int kvm_age_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data)
kpte = kvm_pgtable_stage2_mkold(kvm->arch.mmu.pgt, gpa);
pte = __pte(kpte);
return pte_valid(pte) && pte_young(pte);
+
+ /*
+ * TODO: Handle nested_mmu structures here using the reverse mapping in
+ * a later version of patch series.
+ */
}

static int kvm_test_age_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void *data)
{
WARN_ON(size != PAGE_SIZE && size != PMD_SIZE && size != PUD_SIZE);
return kvm_pgtable_stage2_is_young(kvm->arch.mmu.pgt, gpa);
+
+ /*
+ * TODO: Handle nested_mmu structures here using the reverse mapping in
+ * a later version of patch series.
+ */
}

int kvm_age_hva(struct kvm *kvm, unsigned long start, unsigned long end)
@@ -1457,6 +1482,7 @@ void kvm_arch_flush_shadow_memslot(struct kvm *kvm,

spin_lock(&kvm->mmu_lock);
kvm_unmap_stage2_range(&kvm->arch.mmu, gpa, size);
+ kvm_nested_s2_clear(kvm);
spin_unlock(&kvm->mmu_lock);
}

diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
index 551aee363cc3..e78c6c093afc 100644
--- a/arch/arm64/kvm/nested.c
+++ b/arch/arm64/kvm/nested.c
@@ -505,6 +505,45 @@ int kvm_inject_s2_fault(struct kvm_vcpu *vcpu, u64 esr_el2)
return kvm_inject_nested_sync(vcpu, esr_el2);
}

+/* expects kvm->mmu_lock to be held */
+void kvm_nested_s2_wp(struct kvm *kvm)
+{
+ int i;
+
+ for (i = 0; i < kvm->arch.nested_mmus_size; i++) {
+ struct kvm_s2_mmu *mmu = &kvm->arch.nested_mmus[i];
+
+ if (kvm_s2_mmu_valid(mmu))
+ kvm_stage2_wp_range(mmu, 0, kvm_phys_size(kvm));
+ }
+}
+
+/* expects kvm->mmu_lock to be held */
+void kvm_nested_s2_clear(struct kvm *kvm)
+{
+ int i;
+
+ for (i = 0; i < kvm->arch.nested_mmus_size; i++) {
+ struct kvm_s2_mmu *mmu = &kvm->arch.nested_mmus[i];
+
+ if (kvm_s2_mmu_valid(mmu))
+ kvm_unmap_stage2_range(mmu, 0, kvm_phys_size(kvm));
+ }
+}
+
+/* expects kvm->mmu_lock to be held */
+void kvm_nested_s2_flush(struct kvm *kvm)
+{
+ int i;
+
+ for (i = 0; i < kvm->arch.nested_mmus_size; i++) {
+ struct kvm_s2_mmu *mmu = &kvm->arch.nested_mmus[i];
+
+ if (kvm_s2_mmu_valid(mmu))
+ kvm_stage2_flush_range(mmu, 0, kvm_phys_size(kvm));
+ }
+}
+
/*
* Inject wfx to the virtual EL2 if this is not from the virtual EL2 and
* the virtual HCR_EL2.TWX is set. Otherwise, let the host hypervisor
--
2.29.2