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Subject[RFC 41/55] KVM: arm/arm64: Unmap/flush shadow stage 2 page tables
Date
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. Probably we can do smarter with
some sort of rmap structure.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Jintack Lim <jintack@cs.columbia.edu>
---
arch/arm/include/asm/kvm_mmu.h | 7 ++++
arch/arm/kvm/arm.c | 6 ++-
arch/arm/kvm/mmu.c | 11 +++++
arch/arm64/include/asm/kvm_mmu.h | 13 ++++++
arch/arm64/kvm/mmu-nested.c | 90 ++++++++++++++++++++++++++++++++++++----
5 files changed, 117 insertions(+), 10 deletions(-)

diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h
index 1b3309c..ae3aa39 100644
--- a/arch/arm/include/asm/kvm_mmu.h
+++ b/arch/arm/include/asm/kvm_mmu.h
@@ -230,6 +230,13 @@ static inline unsigned int kvm_get_vmid_bits(void)
return 8;
}

+static inline void kvm_nested_s2_unmap(struct kvm_vcpu *vcpu) { }
+static inline int kvm_nested_s2_init(struct kvm_vcpu *vcpu) { return 0; }
+static inline void kvm_nested_s2_teardown(struct kvm_vcpu *vcpu) { }
+static inline void kvm_nested_s2_all_vcpus_wp(struct kvm *kvm) { }
+static inline void kvm_nested_s2_all_vcpus_unmap(struct kvm *kvm) { }
+static inline void kvm_nested_s2_all_vcpus_flush(struct kvm *kvm) { }
+
static inline u64 kvm_get_vttbr(struct kvm_s2_vmid *vmid,
struct kvm_s2_mmu *mmu)
{
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 6fa5754..dc2795f 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -191,6 +191,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)

for (i = 0; i < KVM_MAX_VCPUS; ++i) {
if (kvm->vcpus[i]) {
+ kvm_nested_s2_teardown(kvm->vcpus[i]);
kvm_arch_vcpu_free(kvm->vcpus[i]);
kvm->vcpus[i] = NULL;
}
@@ -333,6 +334,7 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)

vcpu->arch.hw_mmu = mmu;
vcpu->arch.hw_vttbr = kvm_get_vttbr(&mmu->vmid, mmu);
+ kvm_nested_s2_init(vcpu);

return 0;
}
@@ -871,8 +873,10 @@ static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
* Ensure a rebooted VM will fault in RAM pages and detect if the
* guest MMU is turned off and flush the caches as needed.
*/
- if (vcpu->arch.has_run_once)
+ if (vcpu->arch.has_run_once) {
stage2_unmap_vm(vcpu->kvm);
+ kvm_nested_s2_unmap(vcpu);
+ }

vcpu_reset_hcr(vcpu);

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index 98b42e8..1677a87 100644
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -416,6 +416,8 @@ static void stage2_flush_vm(struct kvm *kvm)
kvm_for_each_memslot(memslot, slots)
stage2_flush_memslot(&kvm->arch.mmu, memslot);

+ kvm_nested_s2_all_vcpus_flush(kvm);
+
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);
}
@@ -1240,6 +1242,7 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot)

spin_lock(&kvm->mmu_lock);
kvm_stage2_wp_range(kvm, &kvm->arch.mmu, start, end);
+ kvm_nested_s2_all_vcpus_wp(kvm);
spin_unlock(&kvm->mmu_lock);
kvm_flush_remote_tlbs(kvm);
}
@@ -1278,6 +1281,7 @@ 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_all_vcpus_wp(kvm);
}

static void coherent_cache_guest_page(struct kvm_vcpu *vcpu, kvm_pfn_t pfn,
@@ -1604,6 +1608,7 @@ static int handle_hva_to_gpa(struct kvm *kvm,
static int kvm_unmap_hva_handler(struct kvm *kvm, gpa_t gpa, void *data)
{
kvm_unmap_stage2_range(&kvm->arch.mmu, gpa, PAGE_SIZE);
+ kvm_nested_s2_all_vcpus_unmap(kvm);
return 0;
}

@@ -1642,6 +1647,7 @@ static int kvm_set_spte_handler(struct kvm *kvm, gpa_t gpa, void *data)
* through this calling path.
*/
stage2_set_pte(&kvm->arch.mmu, NULL, gpa, pte, 0);
+ kvm_nested_s2_all_vcpus_unmap(kvm);
return 0;
}

@@ -1675,6 +1681,8 @@ static int kvm_age_hva_handler(struct kvm *kvm, gpa_t gpa, void *data)
if (pte_none(*pte))
return 0;

+ /* TODO: Handle nested_mmu structures here as well */
+
return stage2_ptep_test_and_clear_young(pte);
}

@@ -1694,6 +1702,8 @@ static int kvm_test_age_hva_handler(struct kvm *kvm, gpa_t gpa, void *data)
if (!pte_none(*pte)) /* Just a page... */
return pte_young(*pte);

+ /* TODO: Handle nested_mmu structures here as well */
+
return 0;
}

@@ -1959,6 +1969,7 @@ 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_all_vcpus_unmap(kvm);
spin_unlock(&kvm->mmu_lock);
}

diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h
index fdc9327..e4d5d54 100644
--- a/arch/arm64/include/asm/kvm_mmu.h
+++ b/arch/arm64/include/asm/kvm_mmu.h
@@ -328,6 +328,12 @@ static inline unsigned int kvm_get_vmid_bits(void)
struct kvm_nested_s2_mmu *get_nested_mmu(struct kvm_vcpu *vcpu, u64 vttbr);
struct kvm_s2_mmu *vcpu_get_active_s2_mmu(struct kvm_vcpu *vcpu);
bool handle_vttbr_update(struct kvm_vcpu *vcpu, u64 vttbr);
+void kvm_nested_s2_unmap(struct kvm_vcpu *vcpu);
+int kvm_nested_s2_init(struct kvm_vcpu *vcpu);
+void kvm_nested_s2_teardown(struct kvm_vcpu *vcpu);
+void kvm_nested_s2_all_vcpus_wp(struct kvm *kvm);
+void kvm_nested_s2_all_vcpus_unmap(struct kvm *kvm);
+void kvm_nested_s2_all_vcpus_flush(struct kvm *kvm);
#else
static inline struct kvm_nested_s2_mmu *get_nested_mmu(struct kvm_vcpu *vcpu,
u64 vttbr)
@@ -343,6 +349,13 @@ static inline bool handle_vttbr_update(struct kvm_vcpu *vcpu, u64 vttbr)
{
return false;
}
+
+static inline void kvm_nested_s2_unmap(struct kvm_vcpu *vcpu) { }
+static inline int kvm_nested_s2_init(struct kvm_vcpu *vcpu) { return 0; }
+static inline void kvm_nested_s2_teardown(struct kvm_vcpu *vcpu) { }
+static inline void kvm_nested_s2_all_vcpus_wp(struct kvm *kvm) { }
+static inline void kvm_nested_s2_all_vcpus_unmap(struct kvm *kvm) { }
+static inline void kvm_nested_s2_all_vcpus_flush(struct kvm *kvm) { }
#endif

static inline u64 kvm_get_vttbr(struct kvm_s2_vmid *vmid,
diff --git a/arch/arm64/kvm/mmu-nested.c b/arch/arm64/kvm/mmu-nested.c
index 0811d94..b22b78c 100644
--- a/arch/arm64/kvm/mmu-nested.c
+++ b/arch/arm64/kvm/mmu-nested.c
@@ -1,6 +1,7 @@
/*
* Copyright (C) 2016 - Columbia University
* Author: Jintack Lim <jintack@cs.columbia.edu>
+ * Author: Christoffer Dall <cdall@cs.columbia.edu>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
@@ -22,6 +23,86 @@
#include <asm/kvm_mmu.h>
#include <asm/kvm_nested.h>

+
+/* expects kvm->mmu_lock to be held */
+void kvm_nested_s2_all_vcpus_wp(struct kvm *kvm)
+{
+ int i;
+ struct kvm_vcpu *vcpu;
+ struct kvm_nested_s2_mmu *nested_mmu;
+ struct list_head *nested_mmu_list;
+
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ if (need_resched() || spin_needbreak(&kvm->mmu_lock))
+ cond_resched_lock(&kvm->mmu_lock);
+
+ nested_mmu_list = &vcpu->kvm->arch.nested_mmu_list;
+ list_for_each_entry_rcu(nested_mmu, nested_mmu_list, list)
+ kvm_stage2_wp_range(kvm, &nested_mmu->mmu,
+ 0, KVM_PHYS_SIZE);
+ }
+}
+
+/* expects kvm->mmu_lock to be held */
+void kvm_nested_s2_all_vcpus_unmap(struct kvm *kvm)
+{
+ int i;
+ struct kvm_vcpu *vcpu;
+ struct kvm_nested_s2_mmu *nested_mmu;
+ struct list_head *nested_mmu_list;
+
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ if (need_resched() || spin_needbreak(&kvm->mmu_lock))
+ cond_resched_lock(&kvm->mmu_lock);
+
+ nested_mmu_list = &vcpu->kvm->arch.nested_mmu_list;
+ list_for_each_entry_rcu(nested_mmu, nested_mmu_list, list)
+ kvm_unmap_stage2_range(&nested_mmu->mmu,
+ 0, KVM_PHYS_SIZE);
+ }
+}
+
+void kvm_nested_s2_all_vcpus_flush(struct kvm *kvm)
+{
+ int i;
+ struct kvm_vcpu *vcpu;
+ struct kvm_nested_s2_mmu *nested_mmu;
+ struct list_head *nested_mmu_list;
+
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ if (need_resched() || spin_needbreak(&kvm->mmu_lock))
+ cond_resched_lock(&kvm->mmu_lock);
+
+ nested_mmu_list = &vcpu->kvm->arch.nested_mmu_list;
+ list_for_each_entry_rcu(nested_mmu, nested_mmu_list, list)
+ kvm_stage2_flush_range(&nested_mmu->mmu,
+ 0, KVM_PHYS_SIZE);
+ }
+}
+
+void kvm_nested_s2_unmap(struct kvm_vcpu *vcpu)
+{
+ struct kvm_nested_s2_mmu *nested_mmu;
+ struct list_head *nested_mmu_list = &vcpu->kvm->arch.nested_mmu_list;
+
+ list_for_each_entry_rcu(nested_mmu, nested_mmu_list, list)
+ kvm_unmap_stage2_range(&nested_mmu->mmu, 0, KVM_PHYS_SIZE);
+}
+
+int kvm_nested_s2_init(struct kvm_vcpu *vcpu)
+{
+ return 0;
+}
+
+void kvm_nested_s2_teardown(struct kvm_vcpu *vcpu)
+{
+ struct kvm_nested_s2_mmu *nested_mmu;
+ struct list_head *nested_mmu_list = &vcpu->kvm->arch.nested_mmu_list;
+
+ list_for_each_entry_rcu(nested_mmu, nested_mmu_list, list)
+ __kvm_free_stage2_pgd(&nested_mmu->mmu);
+}
+
struct kvm_nested_s2_mmu *get_nested_mmu(struct kvm_vcpu *vcpu, u64 vttbr)
{
struct kvm_nested_s2_mmu *mmu;
@@ -89,15 +170,6 @@ static struct kvm_nested_s2_mmu *create_nested_mmu(struct kvm_vcpu *vcpu,
return nested_mmu;
}

-static void kvm_nested_s2_unmap(struct kvm_vcpu *vcpu)
-{
- struct kvm_nested_s2_mmu *nested_mmu;
- struct list_head *nested_mmu_list = &vcpu->kvm->arch.nested_mmu_list;
-
- list_for_each_entry_rcu(nested_mmu, nested_mmu_list, list)
- kvm_unmap_stage2_range(&nested_mmu->mmu, 0, KVM_PHYS_SIZE);
-}
-
bool handle_vttbr_update(struct kvm_vcpu *vcpu, u64 vttbr)
{
struct kvm_nested_s2_mmu *nested_mmu;
--
1.9.1

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