[PATCH v3 4/4] KVM: arm64: Use config_lock to protect vgic state
Oliver Upton
oliver.upton at linux.dev
Mon Mar 27 09:47:47 PDT 2023
Almost all of the vgic state is VM-scoped but accessed from the context
of a vCPU. These accesses were serialized on the kvm->lock which cannot
be nested within a vcpu->mutex critical section.
Move over the vgic state to using the config_lock. Tweak the lock
ordering where necessary to ensure that the config_lock is acquired
after the vcpu->mutex. Acquire the config_lock in kvm_vgic_create() to
avoid a race between the converted flows and GIC creation. Where
necessary, continue to acquire kvm->lock to avoid a race with vCPU
creation (i.e. flows that use lock_all_vcpus()).
Finally, promote the locking expectations in comments to lockdep
assertions and update the locking documentation for the config_lock as
well as vcpu->mutex.
Cc: stable at vger.kernel.org
Signed-off-by: Oliver Upton <oliver.upton at linux.dev>
---
arch/arm64/kvm/vgic/vgic-debug.c | 8 ++---
arch/arm64/kvm/vgic/vgic-init.c | 36 ++++++++++++--------
arch/arm64/kvm/vgic/vgic-its.c | 18 ++++++----
arch/arm64/kvm/vgic/vgic-kvm-device.c | 47 ++++++++++++++++-----------
arch/arm64/kvm/vgic/vgic-mmio-v3.c | 4 +--
arch/arm64/kvm/vgic/vgic-mmio.c | 12 +++----
arch/arm64/kvm/vgic/vgic-v4.c | 11 ++++---
arch/arm64/kvm/vgic/vgic.c | 12 ++++---
8 files changed, 88 insertions(+), 60 deletions(-)
diff --git a/arch/arm64/kvm/vgic/vgic-debug.c b/arch/arm64/kvm/vgic/vgic-debug.c
index 78cde687383c..07aa0437125a 100644
--- a/arch/arm64/kvm/vgic/vgic-debug.c
+++ b/arch/arm64/kvm/vgic/vgic-debug.c
@@ -85,7 +85,7 @@ static void *vgic_debug_start(struct seq_file *s, loff_t *pos)
struct kvm *kvm = s->private;
struct vgic_state_iter *iter;
- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->arch.config_lock);
iter = kvm->arch.vgic.iter;
if (iter) {
iter = ERR_PTR(-EBUSY);
@@ -104,7 +104,7 @@ static void *vgic_debug_start(struct seq_file *s, loff_t *pos)
if (end_of_vgic(iter))
iter = NULL;
out:
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->arch.config_lock);
return iter;
}
@@ -132,12 +132,12 @@ static void vgic_debug_stop(struct seq_file *s, void *v)
if (IS_ERR(v))
return;
- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->arch.config_lock);
iter = kvm->arch.vgic.iter;
kfree(iter->lpi_array);
kfree(iter);
kvm->arch.vgic.iter = NULL;
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->arch.config_lock);
}
static void print_dist_state(struct seq_file *s, struct vgic_dist *dist)
diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index cd134db41a57..9d42c7cb2b58 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -74,9 +74,6 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
unsigned long i;
int ret;
- if (irqchip_in_kernel(kvm))
- return -EEXIST;
-
/*
* This function is also called by the KVM_CREATE_IRQCHIP handler,
* which had no chance yet to check the availability of the GICv2
@@ -87,10 +84,20 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
!kvm_vgic_global_state.can_emulate_gicv2)
return -ENODEV;
+ /* Must be held to avoid race with vCPU creation */
+ lockdep_assert_held(&kvm->lock);
+
ret = -EBUSY;
if (!lock_all_vcpus(kvm))
return ret;
+ mutex_lock(&kvm->arch.config_lock);
+
+ if (irqchip_in_kernel(kvm)) {
+ ret = -EEXIST;
+ goto out_unlock;
+ }
+
kvm_for_each_vcpu(i, vcpu, kvm) {
if (vcpu_has_run_once(vcpu))
goto out_unlock;
@@ -118,6 +125,7 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
INIT_LIST_HEAD(&kvm->arch.vgic.rd_regions);
out_unlock:
+ mutex_unlock(&kvm->arch.config_lock);
unlock_all_vcpus(kvm);
return ret;
}
@@ -227,9 +235,9 @@ int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
* KVM io device for the redistributor that belongs to this VCPU.
*/
if (dist->vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3) {
- mutex_lock(&vcpu->kvm->lock);
+ mutex_lock(&vcpu->kvm->arch.config_lock);
ret = vgic_register_redist_iodev(vcpu);
- mutex_unlock(&vcpu->kvm->lock);
+ mutex_unlock(&vcpu->kvm->arch.config_lock);
}
return ret;
}
@@ -250,7 +258,6 @@ static void kvm_vgic_vcpu_enable(struct kvm_vcpu *vcpu)
* The function is generally called when nr_spis has been explicitly set
* by the guest through the KVM DEVICE API. If not nr_spis is set to 256.
* vgic_initialized() returns true when this function has succeeded.
- * Must be called with kvm->lock held!
*/
int vgic_init(struct kvm *kvm)
{
@@ -259,6 +266,8 @@ int vgic_init(struct kvm *kvm)
int ret = 0, i;
unsigned long idx;
+ lockdep_assert_held(&kvm->arch.config_lock);
+
if (vgic_initialized(kvm))
return 0;
@@ -373,12 +382,13 @@ void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
vgic_cpu->rd_iodev.base_addr = VGIC_ADDR_UNDEF;
}
-/* To be called with kvm->lock held */
static void __kvm_vgic_destroy(struct kvm *kvm)
{
struct kvm_vcpu *vcpu;
unsigned long i;
+ lockdep_assert_held(&kvm->arch.config_lock);
+
vgic_debug_destroy(kvm);
kvm_for_each_vcpu(i, vcpu, kvm)
@@ -389,9 +399,9 @@ static void __kvm_vgic_destroy(struct kvm *kvm)
void kvm_vgic_destroy(struct kvm *kvm)
{
- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->arch.config_lock);
__kvm_vgic_destroy(kvm);
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->arch.config_lock);
}
/**
@@ -414,9 +424,9 @@ int vgic_lazy_init(struct kvm *kvm)
if (kvm->arch.vgic.vgic_model != KVM_DEV_TYPE_ARM_VGIC_V2)
return -EBUSY;
- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->arch.config_lock);
ret = vgic_init(kvm);
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->arch.config_lock);
}
return ret;
@@ -441,7 +451,7 @@ int kvm_vgic_map_resources(struct kvm *kvm)
if (likely(vgic_ready(kvm)))
return 0;
- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->arch.config_lock);
if (vgic_ready(kvm))
goto out;
@@ -459,7 +469,7 @@ int kvm_vgic_map_resources(struct kvm *kvm)
dist->ready = true;
out:
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->arch.config_lock);
return ret;
}
diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index 2642e9ce2819..7713cd06104e 100644
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -2045,6 +2045,13 @@ static int vgic_its_attr_regs_access(struct kvm_device *dev,
mutex_lock(&dev->kvm->lock);
+ if (!lock_all_vcpus(dev->kvm)) {
+ mutex_unlock(&dev->kvm->lock);
+ return -EBUSY;
+ }
+
+ mutex_lock(&dev->kvm->arch.config_lock);
+
if (IS_VGIC_ADDR_UNDEF(its->vgic_its_base)) {
ret = -ENXIO;
goto out;
@@ -2058,11 +2065,6 @@ static int vgic_its_attr_regs_access(struct kvm_device *dev,
goto out;
}
- if (!lock_all_vcpus(dev->kvm)) {
- ret = -EBUSY;
- goto out;
- }
-
addr = its->vgic_its_base + offset;
len = region->access_flags & VGIC_ACCESS_64bit ? 8 : 4;
@@ -2076,8 +2078,9 @@ static int vgic_its_attr_regs_access(struct kvm_device *dev,
} else {
*reg = region->its_read(dev->kvm, its, addr, len);
}
- unlock_all_vcpus(dev->kvm);
out:
+ mutex_unlock(&dev->kvm->arch.config_lock);
+ unlock_all_vcpus(dev->kvm);
mutex_unlock(&dev->kvm->lock);
return ret;
}
@@ -2757,6 +2760,8 @@ static int vgic_its_ctrl(struct kvm *kvm, struct vgic_its *its, u64 attr)
return -EBUSY;
}
+ mutex_lock(&kvm->arch.config_lock);
+
switch (attr) {
case KVM_DEV_ARM_ITS_CTRL_RESET:
vgic_its_reset(kvm, its);
@@ -2769,6 +2774,7 @@ static int vgic_its_ctrl(struct kvm *kvm, struct vgic_its *its, u64 attr)
break;
}
+ mutex_unlock(&kvm->arch.config_lock);
unlock_all_vcpus(kvm);
mutex_unlock(&its->its_lock);
mutex_unlock(&kvm->lock);
diff --git a/arch/arm64/kvm/vgic/vgic-kvm-device.c b/arch/arm64/kvm/vgic/vgic-kvm-device.c
index edeac2380591..07e727023deb 100644
--- a/arch/arm64/kvm/vgic/vgic-kvm-device.c
+++ b/arch/arm64/kvm/vgic/vgic-kvm-device.c
@@ -46,7 +46,7 @@ int kvm_set_legacy_vgic_v2_addr(struct kvm *kvm, struct kvm_arm_device_addr *dev
struct vgic_dist *vgic = &kvm->arch.vgic;
int r;
- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->arch.config_lock);
switch (FIELD_GET(KVM_ARM_DEVICE_TYPE_MASK, dev_addr->id)) {
case KVM_VGIC_V2_ADDR_TYPE_DIST:
r = vgic_check_type(kvm, KVM_DEV_TYPE_ARM_VGIC_V2);
@@ -68,7 +68,7 @@ int kvm_set_legacy_vgic_v2_addr(struct kvm *kvm, struct kvm_arm_device_addr *dev
r = -ENODEV;
}
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->arch.config_lock);
return r;
}
@@ -102,7 +102,7 @@ static int kvm_vgic_addr(struct kvm *kvm, struct kvm_device_attr *attr, bool wri
if (get_user(addr, uaddr))
return -EFAULT;
- mutex_lock(&kvm->lock);
+ mutex_lock(&kvm->arch.config_lock);
switch (attr->attr) {
case KVM_VGIC_V2_ADDR_TYPE_DIST:
r = vgic_check_type(kvm, KVM_DEV_TYPE_ARM_VGIC_V2);
@@ -191,7 +191,7 @@ static int kvm_vgic_addr(struct kvm *kvm, struct kvm_device_attr *attr, bool wri
}
out:
- mutex_unlock(&kvm->lock);
+ mutex_unlock(&kvm->arch.config_lock);
if (!r && !write)
r = put_user(addr, uaddr);
@@ -227,7 +227,7 @@ static int vgic_set_common_attr(struct kvm_device *dev,
(val & 31))
return -EINVAL;
- mutex_lock(&dev->kvm->lock);
+ mutex_lock(&dev->kvm->arch.config_lock);
if (vgic_ready(dev->kvm) || dev->kvm->arch.vgic.nr_spis)
ret = -EBUSY;
@@ -235,16 +235,16 @@ static int vgic_set_common_attr(struct kvm_device *dev,
dev->kvm->arch.vgic.nr_spis =
val - VGIC_NR_PRIVATE_IRQS;
- mutex_unlock(&dev->kvm->lock);
+ mutex_unlock(&dev->kvm->arch.config_lock);
return ret;
}
case KVM_DEV_ARM_VGIC_GRP_CTRL: {
switch (attr->attr) {
case KVM_DEV_ARM_VGIC_CTRL_INIT:
- mutex_lock(&dev->kvm->lock);
+ mutex_lock(&dev->kvm->arch.config_lock);
r = vgic_init(dev->kvm);
- mutex_unlock(&dev->kvm->lock);
+ mutex_unlock(&dev->kvm->arch.config_lock);
return r;
case KVM_DEV_ARM_VGIC_SAVE_PENDING_TABLES:
/*
@@ -260,7 +260,10 @@ static int vgic_set_common_attr(struct kvm_device *dev,
mutex_unlock(&dev->kvm->lock);
return -EBUSY;
}
+
+ mutex_lock(&dev->kvm->arch.config_lock);
r = vgic_v3_save_pending_tables(dev->kvm);
+ mutex_unlock(&dev->kvm->arch.config_lock);
unlock_all_vcpus(dev->kvm);
mutex_unlock(&dev->kvm->lock);
return r;
@@ -411,15 +414,17 @@ static int vgic_v2_attr_regs_access(struct kvm_device *dev,
mutex_lock(&dev->kvm->lock);
+ if (!lock_all_vcpus(dev->kvm)) {
+ mutex_unlock(&dev->kvm->lock);
+ return -EBUSY;
+ }
+
+ mutex_lock(&dev->kvm->arch.config_lock);
+
ret = vgic_init(dev->kvm);
if (ret)
goto out;
- if (!lock_all_vcpus(dev->kvm)) {
- ret = -EBUSY;
- goto out;
- }
-
switch (attr->group) {
case KVM_DEV_ARM_VGIC_GRP_CPU_REGS:
ret = vgic_v2_cpuif_uaccess(vcpu, is_write, addr, &val);
@@ -432,8 +437,9 @@ static int vgic_v2_attr_regs_access(struct kvm_device *dev,
break;
}
- unlock_all_vcpus(dev->kvm);
out:
+ mutex_unlock(&dev->kvm->arch.config_lock);
+ unlock_all_vcpus(dev->kvm);
mutex_unlock(&dev->kvm->lock);
if (!ret && !is_write)
@@ -569,12 +575,14 @@ static int vgic_v3_attr_regs_access(struct kvm_device *dev,
mutex_lock(&dev->kvm->lock);
- if (unlikely(!vgic_initialized(dev->kvm))) {
- ret = -EBUSY;
- goto out;
+ if (!lock_all_vcpus(dev->kvm)) {
+ mutex_unlock(&dev->kvm->lock);
+ return -EBUSY;
}
- if (!lock_all_vcpus(dev->kvm)) {
+ mutex_lock(&dev->kvm->arch.config_lock);
+
+ if (unlikely(!vgic_initialized(dev->kvm))) {
ret = -EBUSY;
goto out;
}
@@ -609,8 +617,9 @@ static int vgic_v3_attr_regs_access(struct kvm_device *dev,
break;
}
- unlock_all_vcpus(dev->kvm);
out:
+ mutex_unlock(&dev->kvm->arch.config_lock);
+ unlock_all_vcpus(dev->kvm);
mutex_unlock(&dev->kvm->lock);
if (!ret && uaccess && !is_write) {
diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
index 91201f743033..472b18ac92a2 100644
--- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
@@ -111,7 +111,7 @@ static void vgic_mmio_write_v3_misc(struct kvm_vcpu *vcpu,
case GICD_CTLR: {
bool was_enabled, is_hwsgi;
- mutex_lock(&vcpu->kvm->lock);
+ mutex_lock(&vcpu->kvm->arch.config_lock);
was_enabled = dist->enabled;
is_hwsgi = dist->nassgireq;
@@ -139,7 +139,7 @@ static void vgic_mmio_write_v3_misc(struct kvm_vcpu *vcpu,
else if (!was_enabled && dist->enabled)
vgic_kick_vcpus(vcpu->kvm);
- mutex_unlock(&vcpu->kvm->lock);
+ mutex_unlock(&vcpu->kvm->arch.config_lock);
break;
}
case GICD_TYPER:
diff --git a/arch/arm64/kvm/vgic/vgic-mmio.c b/arch/arm64/kvm/vgic/vgic-mmio.c
index e67b3b2c8044..1939c94e0b24 100644
--- a/arch/arm64/kvm/vgic/vgic-mmio.c
+++ b/arch/arm64/kvm/vgic/vgic-mmio.c
@@ -530,13 +530,13 @@ unsigned long vgic_mmio_read_active(struct kvm_vcpu *vcpu,
u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
u32 val;
- mutex_lock(&vcpu->kvm->lock);
+ mutex_lock(&vcpu->kvm->arch.config_lock);
vgic_access_active_prepare(vcpu, intid);
val = __vgic_mmio_read_active(vcpu, addr, len);
vgic_access_active_finish(vcpu, intid);
- mutex_unlock(&vcpu->kvm->lock);
+ mutex_unlock(&vcpu->kvm->arch.config_lock);
return val;
}
@@ -625,13 +625,13 @@ void vgic_mmio_write_cactive(struct kvm_vcpu *vcpu,
{
u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
- mutex_lock(&vcpu->kvm->lock);
+ mutex_lock(&vcpu->kvm->arch.config_lock);
vgic_access_active_prepare(vcpu, intid);
__vgic_mmio_write_cactive(vcpu, addr, len, val);
vgic_access_active_finish(vcpu, intid);
- mutex_unlock(&vcpu->kvm->lock);
+ mutex_unlock(&vcpu->kvm->arch.config_lock);
}
int vgic_mmio_uaccess_write_cactive(struct kvm_vcpu *vcpu,
@@ -662,13 +662,13 @@ void vgic_mmio_write_sactive(struct kvm_vcpu *vcpu,
{
u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
- mutex_lock(&vcpu->kvm->lock);
+ mutex_lock(&vcpu->kvm->arch.config_lock);
vgic_access_active_prepare(vcpu, intid);
__vgic_mmio_write_sactive(vcpu, addr, len, val);
vgic_access_active_finish(vcpu, intid);
- mutex_unlock(&vcpu->kvm->lock);
+ mutex_unlock(&vcpu->kvm->arch.config_lock);
}
int vgic_mmio_uaccess_write_sactive(struct kvm_vcpu *vcpu,
diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c
index a413718be92b..3bb003478060 100644
--- a/arch/arm64/kvm/vgic/vgic-v4.c
+++ b/arch/arm64/kvm/vgic/vgic-v4.c
@@ -232,9 +232,8 @@ int vgic_v4_request_vpe_irq(struct kvm_vcpu *vcpu, int irq)
* @kvm: Pointer to the VM being initialized
*
* We may be called each time a vITS is created, or when the
- * vgic is initialized. This relies on kvm->lock to be
- * held. In both cases, the number of vcpus should now be
- * fixed.
+ * vgic is initialized. In both cases, the number of vcpus
+ * should now be fixed.
*/
int vgic_v4_init(struct kvm *kvm)
{
@@ -243,6 +242,8 @@ int vgic_v4_init(struct kvm *kvm)
int nr_vcpus, ret;
unsigned long i;
+ lockdep_assert_held(&kvm->arch.config_lock);
+
if (!kvm_vgic_global_state.has_gicv4)
return 0; /* Nothing to see here... move along. */
@@ -309,14 +310,14 @@ int vgic_v4_init(struct kvm *kvm)
/**
* vgic_v4_teardown - Free the GICv4 data structures
* @kvm: Pointer to the VM being destroyed
- *
- * Relies on kvm->lock to be held.
*/
void vgic_v4_teardown(struct kvm *kvm)
{
struct its_vm *its_vm = &kvm->arch.vgic.its_vm;
int i;
+ lockdep_assert_held(&kvm->arch.config_lock);
+
if (!its_vm->vpes)
return;
diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
index d97e6080b421..0a005da83ae6 100644
--- a/arch/arm64/kvm/vgic/vgic.c
+++ b/arch/arm64/kvm/vgic/vgic.c
@@ -24,11 +24,13 @@ struct vgic_global kvm_vgic_global_state __ro_after_init = {
/*
* Locking order is always:
* kvm->lock (mutex)
- * its->cmd_lock (mutex)
- * its->its_lock (mutex)
- * vgic_cpu->ap_list_lock must be taken with IRQs disabled
- * kvm->lpi_list_lock must be taken with IRQs disabled
- * vgic_irq->irq_lock must be taken with IRQs disabled
+ * vcpu->mutex (mutex)
+ * kvm->arch.config_lock (mutex)
+ * its->cmd_lock (mutex)
+ * its->its_lock (mutex)
+ * vgic_cpu->ap_list_lock must be taken with IRQs disabled
+ * kvm->lpi_list_lock must be taken with IRQs disabled
+ * vgic_irq->irq_lock must be taken with IRQs disabled
*
* As the ap_list_lock might be taken from the timer interrupt handler,
* we have to disable IRQs before taking this lock and everything lower
--
2.40.0.348.gf938b09366-goog
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