[PATCH v8 13/17] KVM: arm64: read initial LPI pending table

Andre Przywara
2016-07-05T11:22:46Z

The LPI pending status for a GICv3 redistributor is held in a table
in (guest) memory. To achieve reasonable performance, we cache this
data in our struct vgic_irq. The initial pending state must be read
from guest memory upon enabling LPIs for this redistributor.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
virt/kvm/arm/vgic/vgic-its.c | 81 ++++++++++++++++++++++++++++++++++++++++++++
virt/kvm/arm/vgic/vgic.h | 6 ++++
2 files changed, 87 insertions(+)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 1e2e649..29bb4fe 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -93,6 +93,81 @@ struct its_itte {
list_for_each_entry(itte, &(dev)->itt_head, itte_list)

#define CBASER_ADDRESS(x) ((x) & GENMASK_ULL(51, 12))
+#define PENDBASER_ADDRESS(x) ((x) & GENMASK_ULL(51, 16))
+
+static int vgic_its_copy_lpi_list(struct kvm *kvm, u32 **intid_ptr)
+{
+ struct vgic_dist *dist = &kvm->arch.vgic;
+ struct vgic_irq *irq;
+ u32 *intids;
+ int irq_count = dist->lpi_list_count, i = 0;
+
+ /*
+ * We use the current value of the list length, which may change
+ * after the kmalloc. We don't care, because the guest shouldn't
+ * change anything while the command handling is still running,
+ * and in the worst case we would miss a new IRQ, which one wouldn't
+ * expect to be covered by this command anyway.
+ */
+ intids = kmalloc_array(irq_count, sizeof(intids[0]), GFP_KERNEL);
+ if (!intids)
+ return -ENOMEM;
+
+ spin_lock(&dist->lpi_list_lock);
+ list_for_each_entry(irq, &dist->lpi_list_head, lpi_entry) {
+ if (kref_get_unless_zero(&irq->refcount)) {
+ intids[i] = irq->intid;
+ vgic_put_irq_locked(kvm, irq);
+ }
+ if (i++ == irq_count)
+ break;
+ }
+ spin_unlock(&dist->lpi_list_lock);
+
+ *intid_ptr = intids;
+ return irq_count;
+}
+
+/*
+ * Scan the whole LPI pending table and sync the pending bit in there
+ * with our own data structures. This relies on the LPI being
+ * mapped before.
+ */
+static int its_sync_lpi_pending_table(struct kvm_vcpu *vcpu)
+{
+ gpa_t pendbase = PENDBASER_ADDRESS(vcpu->arch.vgic_cpu.pendbaser);
+ struct vgic_irq *irq;
+ u8 pendmask;
+ int ret = 0;
+ u32 *intids;
+ int nr_irqs, i;
+
+ nr_irqs = vgic_its_copy_lpi_list(vcpu->kvm, &intids);
+ if (nr_irqs < 0)
+ return nr_irqs;
+
+ for (i = 0; i < nr_irqs; i++) {
+ int byte_offset, bit_nr;
+
+ byte_offset = intids[i] / BITS_PER_BYTE;
+ bit_nr = intids[i] % BITS_PER_BYTE;
+
+ ret = kvm_read_guest(vcpu->kvm, pendbase + byte_offset,
+ &pendmask, 1);
+ if (ret) {
+ kfree(intids);
+ return ret;
+ }
+
+ irq = vgic_get_irq(vcpu->kvm, NULL, intids[i]);
+ spin_lock(&irq->irq_lock);
+ irq->pending = pendmask & (1U << bit_nr);
+ vgic_queue_irq_unlock(vcpu->kvm, irq);
+ vgic_put_irq(vcpu->kvm, irq);
+ }
+
+ return ret;
+}

static unsigned long vgic_mmio_read_its_ctlr(struct kvm *vcpu,
struct vgic_its *its,
@@ -415,6 +490,12 @@ static struct vgic_register_region its_registers[] = {
VGIC_ACCESS_32bit),
};

+/* This is called on setting the LPI enable bit in the redistributor. */
+void vgic_enable_lpis(struct kvm_vcpu *vcpu)
+{
+ its_sync_lpi_pending_table(vcpu);
+}
+
static int vgic_its_register(struct kvm *kvm, struct vgic_its *its)
{
struct vgic_io_device *iodev = &its->iodev;
diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
index eef9ec1..4a9165f 100644
--- a/virt/kvm/arm/vgic/vgic.h
+++ b/virt/kvm/arm/vgic/vgic.h
@@ -25,6 +25,7 @@
#define IS_VGIC_ADDR_UNDEF(_x) ((_x) == VGIC_ADDR_UNDEF)

#define INTERRUPT_ID_BITS_SPIS 10
+#define INTERRUPT_ID_BITS_ITS 16
#define VGIC_PRI_BITS 5

#define vgic_irq_is_sgi(intid) ((intid) < VGIC_NR_SGIS)
@@ -79,6 +80,7 @@ int vgic_register_redist_iodevs(struct kvm *kvm, gpa_t dist_base_address);
bool vgic_has_its(struct kvm *kvm);
int kvm_vgic_register_its_device(void);
struct vgic_irq *vgic_its_get_lpi(struct kvm *kvm, u32 intid);
+void vgic_enable_lpis(struct kvm_vcpu *vcpu);
#else
static inline void vgic_v3_process_maintenance(struct kvm_vcpu *vcpu)
{
@@ -145,6 +147,10 @@ static inline struct vgic_irq *vgic_its_get_lpi(struct kvm *kvm, u32 intid)
{
return NULL;
}
+
+static inline void vgic_enable_lpis(struct kvm_vcpu *vcpu)
+{
+}
#endif

int kvm_register_vgic_device(unsigned long type);
--
2.9.0