[PATCH 1/5] arm/arm64: KVM: vgic: move reset initialization into vgic_init_maps()

Christoffer Dall
2014-12-09T15:43:16Z

From: Peter Maydell <peter.maydell@linaro.org>

VGIC initialization currently happens in three phases:
(1) kvm_vgic_create() (triggered by userspace GIC creation)
(2) vgic_init_maps() (triggered by userspace GIC register read/write
requests, or from kvm_vgic_init() if not already run)
(3) kvm_vgic_init() (triggered by first VM run)

We were doing initialization of some state to correspond with the
state of a freshly-reset GIC in kvm_vgic_init(); this is too late,
since it will overwrite changes made by userspace using the
register access APIs before the VM is run. Move this initialization
earlier, into the vgic_init_maps() phase.

This fixes a bug where QEMU could successfully restore a saved
VM state snapshot into a VM that had already been run, but could
not restore it "from cold" using the -loadvm command line option
(the symptoms being that the restored VM would run but interrupts
were ignored).

Finally rename vgic_init_maps to vgic_init and renamed kvm_vgic_init to
kvm_vgic_map_resources.

[ This patch is originally written by Peter Maydell, but I have
modified it somewhat heavily, renaming various bits and moving code
around. If something is broken, I am to be blamed. - Christoffer ]

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
This patch was originally named "vgic: move reset initialization into
vgic_init_maps()" but I renamed it slightly to match the other vgic
patches in the kernel. I also did the additional changes since the
original patch:
- Renamed kvm_vgic_init to kvm_vgic_map_resources
- Renamed vgic_init_maps to vgic_init
- Moved vgic_enable call into existing vcpu loop in vgic_init
- Moved ITARGETSRn initializtion above vcpu loop in vgic_init (the idea
is to init global state first, then vcpu state).
- Added comment in kvm_vgic_map_resources

arch/arm/kvm/arm.c | 6 ++--
include/kvm/arm_vgic.h | 4 +--
virt/kvm/arm/vgic.c | 77 +++++++++++++++++++++-----------------------------
3 files changed, 37 insertions(+), 50 deletions(-)

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 9e193c8..a56cbb5 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -427,11 +427,11 @@ static int kvm_vcpu_first_run_init(struct kvm_vcpu *vcpu)
vcpu->arch.has_run_once = true;

/*
- * Initialize the VGIC before running a vcpu the first time on
- * this VM.
+ * Map the VGIC hardware resources before running a vcpu the first
+ * time on this VM.
*/
if (unlikely(!vgic_initialized(vcpu->kvm))) {
- ret = kvm_vgic_init(vcpu->kvm);
+ ret = kvm_vgic_map_resources(vcpu->kvm);
if (ret)
return ret;
}
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 206dcc3..fe9783b 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -274,7 +274,7 @@ struct kvm_exit_mmio;
#ifdef CONFIG_KVM_ARM_VGIC
int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write);
int kvm_vgic_hyp_init(void);
-int kvm_vgic_init(struct kvm *kvm);
+int kvm_vgic_map_resources(struct kvm *kvm);
int kvm_vgic_create(struct kvm *kvm);
void kvm_vgic_destroy(struct kvm *kvm);
void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu);
@@ -321,7 +321,7 @@ static inline int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr,
return -ENXIO;
}

-static inline int kvm_vgic_init(struct kvm *kvm)
+static inline int kvm_vgic_map_resources(struct kvm *kvm)
{
return 0;
}
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index aacdb59..91e6bfc 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -91,6 +91,7 @@
#define ACCESS_WRITE_VALUE (3 << 1)
#define ACCESS_WRITE_MASK(x) ((x) & (3 << 1))

+static int vgic_init(struct kvm *kvm);
static void vgic_retire_disabled_irqs(struct kvm_vcpu *vcpu);
static void vgic_retire_lr(int lr_nr, int irq, struct kvm_vcpu *vcpu);
static void vgic_update_state(struct kvm *kvm);
@@ -1726,39 +1727,14 @@ static int vgic_vcpu_init_maps(struct kvm_vcpu *vcpu, int nr_irqs)

int sz = (nr_irqs - VGIC_NR_PRIVATE_IRQS) / 8;
vgic_cpu->pending_shared = kzalloc(sz, GFP_KERNEL);
- vgic_cpu->vgic_irq_lr_map = kzalloc(nr_irqs, GFP_KERNEL);
+ vgic_cpu->vgic_irq_lr_map = kmalloc(nr_irqs, GFP_KERNEL);

if (!vgic_cpu->pending_shared || !vgic_cpu->vgic_irq_lr_map) {
kvm_vgic_vcpu_destroy(vcpu);
return -ENOMEM;
}

- return 0;
-}
-
-/**
- * kvm_vgic_vcpu_init - Initialize per-vcpu VGIC state
- * @vcpu: pointer to the vcpu struct
- *
- * Initialize the vgic_cpu struct and vgic_dist struct fields pertaining to
- * this vcpu and enable the VGIC for this VCPU
- */
-static void kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
-{
- struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
- struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
- int i;
-
- for (i = 0; i < dist->nr_irqs; i++) {
- if (i < VGIC_NR_PPIS)
- vgic_bitmap_set_irq_val(&dist->irq_enabled,
- vcpu->vcpu_id, i, 1);
- if (i < VGIC_NR_PRIVATE_IRQS)
- vgic_bitmap_set_irq_val(&dist->irq_cfg,
- vcpu->vcpu_id, i, VGIC_CFG_EDGE);
-
- vgic_cpu->vgic_irq_lr_map[i] = LR_EMPTY;
- }
+ memset(vgic_cpu->vgic_irq_lr_map, LR_EMPTY, nr_irqs);

/*
* Store the number of LRs per vcpu, so we don't have to go
@@ -1767,7 +1743,7 @@ static void kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
*/
vgic_cpu->nr_lr = vgic->nr_lr;

- vgic_enable(vcpu);
+ return 0;
}

void kvm_vgic_destroy(struct kvm *kvm)
@@ -1804,12 +1780,12 @@ void kvm_vgic_destroy(struct kvm *kvm)
* Allocate and initialize the various data structures. Must be called
* with kvm->lock held!
*/
-static int vgic_init_maps(struct kvm *kvm)
+static int vgic_init(struct kvm *kvm)
{
struct vgic_dist *dist = &kvm->arch.vgic;
struct kvm_vcpu *vcpu;
int nr_cpus, nr_irqs;
- int ret, i;
+ int ret, i, vcpu_id;

if (dist->nr_cpus) /* Already allocated */
return 0;
@@ -1859,16 +1835,28 @@ static int vgic_init_maps(struct kvm *kvm)
if (ret)
goto out;

- kvm_for_each_vcpu(i, vcpu, kvm) {
+ for (i = VGIC_NR_PRIVATE_IRQS; i < dist->nr_irqs; i += 4)
+ vgic_set_target_reg(kvm, 0, i);
+
+ kvm_for_each_vcpu(vcpu_id, vcpu, kvm) {
ret = vgic_vcpu_init_maps(vcpu, nr_irqs);
if (ret) {
kvm_err("VGIC: Failed to allocate vcpu memory\n");
break;
}
- }

- for (i = VGIC_NR_PRIVATE_IRQS; i < dist->nr_irqs; i += 4)
- vgic_set_target_reg(kvm, 0, i);
+ for (i = 0; i < dist->nr_irqs; i++) {
+ if (i < VGIC_NR_PPIS)
+ vgic_bitmap_set_irq_val(&dist->irq_enabled,
+ vcpu->vcpu_id, i, 1);
+ if (i < VGIC_NR_PRIVATE_IRQS)
+ vgic_bitmap_set_irq_val(&dist->irq_cfg,
+ vcpu->vcpu_id, i,
+ VGIC_CFG_EDGE);
+ }
+
+ vgic_enable(vcpu);
+ }

out:
if (ret)
@@ -1878,18 +1866,16 @@ out:
}

/**
- * kvm_vgic_init - Initialize global VGIC state before running any VCPUs
+ * kvm_vgic_map_resources - Configure global VGIC state before running any VCPUs
* @kvm: pointer to the kvm struct
*
* Map the virtual CPU interface into the VM before running any VCPUs. We
* can't do this at creation time, because user space must first set the
- * virtual CPU interface address in the guest physical address space. Also
- * initialize the ITARGETSRn regs to 0 on the emulated distributor.
+ * virtual CPU interface address in the guest physical address space.
*/
-int kvm_vgic_init(struct kvm *kvm)
+int kvm_vgic_map_resources(struct kvm *kvm)
{
- struct kvm_vcpu *vcpu;
- int ret = 0, i;
+ int ret = 0;

if (!irqchip_in_kernel(kvm))
return 0;
@@ -1906,7 +1892,11 @@ int kvm_vgic_init(struct kvm *kvm)
goto out;
}

- ret = vgic_init_maps(kvm);
+ /*
+ * Initialize the vgic if this hasn't already been done on demand by
+ * accessing the vgic state from userspace.
+ */
+ ret = vgic_init(kvm);
if (ret) {
kvm_err("Unable to allocate maps\n");
goto out;
@@ -1920,9 +1910,6 @@ int kvm_vgic_init(struct kvm *kvm)
goto out;
}

- kvm_for_each_vcpu(i, vcpu, kvm)
- kvm_vgic_vcpu_init(vcpu);
-
kvm->arch.vgic.ready = true;
out:
if (ret)
@@ -2167,7 +2154,7 @@ static int vgic_attr_regs_access(struct kvm_device *dev,

mutex_lock(&dev->kvm->lock);

- ret = vgic_init_maps(dev->kvm);
+ ret = vgic_init(dev->kvm);
if (ret)
goto out;

--
2.1.2.330.g565301e.dirty