From: Ben Gardon <bgardon@google.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Peter Shier <pshier@google.com>,
Junaid Shahid <junaids@google.com>,
Jim Mattson <jmattson@google.com>,
Yulei Zhang <yulei.kernel@gmail.com>,
Wanpeng Li <kernellwp@gmail.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Xiao Guangrong <xiaoguangrong.eric@gmail.com>,
Ben Gardon <bgardon@google.com>
Subject: [PATCH 5/6] KVM: x86/mmu: Protect kvm->memslots with a mutex
Date: Tue, 27 Apr 2021 15:36:34 -0700 [thread overview]
Message-ID: <20210427223635.2711774-6-bgardon@google.com> (raw)
In-Reply-To: <20210427223635.2711774-1-bgardon@google.com>
Adds a lock around memslots changes. Currently this lock does not have
any effect on the syncronization model, but it will be used in a future
commit to facilitate lazy rmap allocation.
Signed-off-by: Ben Gardon <bgardon@google.com>
---
arch/x86/include/asm/kvm_host.h | 5 +++++
arch/x86/kvm/x86.c | 11 +++++++++++
include/linux/kvm_host.h | 2 ++
virt/kvm/kvm_main.c | 9 ++++++++-
4 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3900dcf2439e..bce7fa152473 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1124,6 +1124,11 @@ struct kvm_arch {
#endif /* CONFIG_X86_64 */
bool shadow_mmu_active;
+
+ /*
+ * Protects kvm->memslots.
+ */
+ struct mutex memslot_assignment_lock;
};
struct kvm_vm_stat {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fc32a7dbe4c4..30234fe96f48 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10649,6 +10649,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
raw_spin_lock_init(&kvm->arch.tsc_write_lock);
mutex_init(&kvm->arch.apic_map_lock);
spin_lock_init(&kvm->arch.pvclock_gtod_sync_lock);
+ mutex_init(&kvm->arch.memslot_assignment_lock);
kvm->arch.kvmclock_offset = -get_kvmclock_base_ns();
pvclock_update_vm_gtod_copy(kvm);
@@ -10868,6 +10869,16 @@ static int alloc_memslot_rmap(struct kvm_memory_slot *slot,
return -ENOMEM;
}
+
+void kvm_arch_assign_memslots(struct kvm *kvm, int as_id,
+ struct kvm_memslots *slots)
+{
+ mutex_lock(&kvm->arch.memslot_assignment_lock);
+ rcu_assign_pointer(kvm->memslots[as_id], slots);
+ mutex_unlock(&kvm->arch.memslot_assignment_lock);
+}
+
+
static int kvm_alloc_memslot_metadata(struct kvm_memory_slot *slot,
unsigned long npages)
{
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 8895b95b6a22..146bb839c754 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -720,6 +720,8 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
struct kvm_memory_slot *memslot,
const struct kvm_userspace_memory_region *mem,
enum kvm_mr_change change);
+void kvm_arch_assign_memslots(struct kvm *kvm, int as_id,
+ struct kvm_memslots *slots);
void kvm_arch_commit_memory_region(struct kvm *kvm,
const struct kvm_userspace_memory_region *mem,
struct kvm_memory_slot *old,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2799c6660cce..e62a37bc5b90 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1270,6 +1270,12 @@ static int check_memory_region_flags(const struct kvm_userspace_memory_region *m
return 0;
}
+__weak void kvm_arch_assign_memslots(struct kvm *kvm, int as_id,
+ struct kvm_memslots *slots)
+{
+ rcu_assign_pointer(kvm->memslots[as_id], slots);
+}
+
static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
int as_id, struct kvm_memslots *slots)
{
@@ -1279,7 +1285,8 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
WARN_ON(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS);
slots->generation = gen | KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS;
- rcu_assign_pointer(kvm->memslots[as_id], slots);
+ kvm_arch_assign_memslots(kvm, as_id, slots);
+
synchronize_srcu_expedited(&kvm->srcu);
/*
--
2.31.1.498.g6c1eba8ee3d-goog
next prev parent reply other threads:[~2021-04-27 22:36 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-27 22:36 [PATCH 0/6] Lazily allocate memslot rmaps Ben Gardon
2021-04-27 22:36 ` [PATCH 1/6] KVM: x86/mmu: Track if shadow MMU active Ben Gardon
2021-04-27 22:36 ` [PATCH 2/6] KVM: x86/mmu: Skip rmap operations if shadow MMU inactive Ben Gardon
2021-04-27 22:36 ` [PATCH 3/6] KVM: x86/mmu: Deduplicate rmap freeing in allocate_memslot_rmap Ben Gardon
2021-04-28 10:00 ` Paolo Bonzini
2021-04-28 16:23 ` Ben Gardon
2021-04-27 22:36 ` [PATCH 4/6] KVM: x86/mmu: Factor out allocating memslot rmap Ben Gardon
2021-04-27 22:36 ` Ben Gardon [this message]
2021-04-28 6:25 ` [PATCH 5/6] KVM: x86/mmu: Protect kvm->memslots with a mutex Paolo Bonzini
2021-04-28 16:40 ` Ben Gardon
2021-04-28 17:46 ` Paolo Bonzini
2021-04-28 20:40 ` Ben Gardon
2021-04-28 21:41 ` Paolo Bonzini
2021-04-28 21:46 ` Ben Gardon
2021-04-28 23:42 ` Paolo Bonzini
2021-04-29 0:40 ` Sean Christopherson
2021-04-29 1:42 ` Sean Christopherson
2021-04-29 7:02 ` Paolo Bonzini
2021-04-29 17:45 ` Ben Gardon
2021-04-27 22:36 ` [PATCH 6/6] KVM: x86/mmu: Lazily allocate memslot rmaps Ben Gardon
2021-04-28 10:03 ` Paolo Bonzini
2021-04-28 16:45 ` Ben Gardon
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