[PATCH 2/4] KVM: arm64: vgic-v3: Implement MMIO-based LPI invalidation

Marc Zyngier
2022-03-14T16:42:56Z

Since GICv4.1, it has become legal for an implementation to advertise
GICR_{INVLPIR,INVALLR,SYNCR} while having an ITS, allowing for a more
efficient invalidation scheme (no guest command queue contention when
multiple CPUs are generating invalidations).

Provide the invalidation registers as a primitive to their ITS
counterpart. Note that we don't advertise them to the guest yet
(the architecture allows an implementation to do this).

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/kvm/vgic/vgic-its.c | 62 ++++++++++++++++++++----------
arch/arm64/kvm/vgic/vgic-mmio-v3.c | 62 ++++++++++++++++++++++++++++++
arch/arm64/kvm/vgic/vgic.h | 4 ++
include/kvm/arm_vgic.h | 1 +
4 files changed, 108 insertions(+), 21 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index 089fc2ffcb43..cc62d8a8180f 100644
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -1272,6 +1272,11 @@ static int vgic_its_cmd_handle_clear(struct kvm *kvm, struct vgic_its *its,
return 0;
}

+int vgic_its_inv_lpi(struct kvm *kvm, struct vgic_irq *irq)
+{
+ return update_lpi_config(kvm, irq, NULL, true);
+}
+
/*
* The INV command syncs the configuration bits from the memory table.
* Must be called with the its_lock mutex held.
@@ -1288,7 +1293,41 @@ static int vgic_its_cmd_handle_inv(struct kvm *kvm, struct vgic_its *its,
if (!ite)
return E_ITS_INV_UNMAPPED_INTERRUPT;

- return update_lpi_config(kvm, ite->irq, NULL, true);
+ return vgic_its_inv_lpi(kvm, ite->irq);
+}
+
+/**
+ * vgic_its_invall - invalidate all LPIs targetting a given vcpu
+ * @vcpu: the vcpu for which the RD is targetted by an invalidation
+ *
+ * Contrary to the INVALL command, this targets a RD instead of a
+ * collection, and we don't need to hold the its_lock, since no ITS is
+ * involved here.
+ */
+int vgic_its_invall(struct kvm_vcpu *vcpu)
+{
+ struct kvm *kvm = vcpu->kvm;
+ int irq_count, i = 0;
+ u32 *intids;
+
+ irq_count = vgic_copy_lpi_list(kvm, vcpu, &intids);
+ if (irq_count < 0)
+ return irq_count;
+
+ for (i = 0; i < irq_count; i++) {
+ struct vgic_irq *irq = vgic_get_irq(kvm, NULL, intids[i]);
+ if (!irq)
+ continue;
+ update_lpi_config(kvm, irq, vcpu, false);
+ vgic_put_irq(kvm, irq);
+ }
+
+ kfree(intids);
+
+ if (vcpu->arch.vgic_cpu.vgic_v3.its_vpe.its_vm)
+ its_invall_vpe(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe);
+
+ return 0;
}

/*
@@ -1305,32 +1344,13 @@ static int vgic_its_cmd_handle_invall(struct kvm *kvm, struct vgic_its *its,
u32 coll_id = its_cmd_get_collection(its_cmd);
struct its_collection *collection;
struct kvm_vcpu *vcpu;
- struct vgic_irq *irq;
- u32 *intids;
- int irq_count, i;

collection = find_collection(its, coll_id);
if (!its_is_collection_mapped(collection))
return E_ITS_INVALL_UNMAPPED_COLLECTION;

vcpu = kvm_get_vcpu(kvm, collection->target_addr);
-
- irq_count = vgic_copy_lpi_list(kvm, vcpu, &intids);
- if (irq_count < 0)
- return irq_count;
-
- for (i = 0; i < irq_count; i++) {
- irq = vgic_get_irq(kvm, NULL, intids[i]);
- if (!irq)
- continue;
- update_lpi_config(kvm, irq, vcpu, false);
- vgic_put_irq(kvm, irq);
- }
-
- kfree(intids);
-
- if (vcpu->arch.vgic_cpu.vgic_v3.its_vpe.its_vm)
- its_invall_vpe(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe);
+ vgic_its_invall(vcpu);

return 0;
}
diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
index 58e40b4874f8..186bf35078bf 100644
--- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
@@ -525,6 +525,59 @@ static void vgic_mmio_write_pendbase(struct kvm_vcpu *vcpu,
pendbaser) != old_pendbaser);
}

+static unsigned long vgic_mmio_read_sync(struct kvm_vcpu *vcpu,
+ gpa_t addr, unsigned int len)
+{
+ return !!atomic_read(&vcpu->arch.vgic_cpu.syncr_busy);
+}
+
+static void vgic_make_rdist_busy(struct kvm_vcpu *vcpu, bool busy)
+{
+ if (busy) {
+ atomic_inc(&vcpu->arch.vgic_cpu.syncr_busy);
+ smp_mb__after_atomic();
+ } else {
+ smp_mb__before_atomic();
+ atomic_dec(&vcpu->arch.vgic_cpu.syncr_busy);
+ }
+}
+
+static void vgic_mmio_write_invlpi(struct kvm_vcpu *vcpu,
+ gpa_t addr, unsigned int len,
+ unsigned long val)
+{
+ struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+ struct vgic_irq *irq;
+
+ if (!vgic_cpu->lpis_enabled)
+ return;
+
+ vgic_make_rdist_busy(vcpu, true);
+
+ irq = vgic_get_irq(vcpu->kvm, NULL, val);
+ if (!irq)
+ return;
+
+ vgic_its_inv_lpi(vcpu->kvm, irq);
+ vgic_put_irq(vcpu->kvm, irq);
+
+ vgic_make_rdist_busy(vcpu, false);
+}
+
+static void vgic_mmio_write_invall(struct kvm_vcpu *vcpu,
+ gpa_t addr, unsigned int len,
+ unsigned long val)
+{
+ struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
+
+ if (!vgic_cpu->lpis_enabled)
+ return;
+
+ vgic_make_rdist_busy(vcpu, true);
+ vgic_its_invall(vcpu);
+ vgic_make_rdist_busy(vcpu, false);
+}
+
/*
* The GICv3 per-IRQ registers are split to control PPIs and SGIs in the
* redistributors, while SPIs are covered by registers in the distributor
@@ -630,6 +683,15 @@ static const struct vgic_register_region vgic_v3_rd_registers[] = {
REGISTER_DESC_WITH_LENGTH(GICR_PENDBASER,
vgic_mmio_read_pendbase, vgic_mmio_write_pendbase, 8,
VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
+ REGISTER_DESC_WITH_LENGTH(GICR_INVLPIR,
+ vgic_mmio_read_raz, vgic_mmio_write_invlpi, 8,
+ VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
+ REGISTER_DESC_WITH_LENGTH(GICR_INVALLR,
+ vgic_mmio_read_raz, vgic_mmio_write_invall, 8,
+ VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
+ REGISTER_DESC_WITH_LENGTH(GICR_SYNCR,
+ vgic_mmio_read_sync, vgic_mmio_write_wi, 8,
+ VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
REGISTER_DESC_WITH_LENGTH(GICR_IDREGS,
vgic_mmio_read_v3_idregs, vgic_mmio_write_wi, 48,
VGIC_ACCESS_32bit),
diff --git a/arch/arm64/kvm/vgic/vgic.h b/arch/arm64/kvm/vgic/vgic.h
index 3fd6c86a7ef3..53581e11f7c8 100644
--- a/arch/arm64/kvm/vgic/vgic.h
+++ b/arch/arm64/kvm/vgic/vgic.h
@@ -317,6 +317,10 @@ void vgic_lpi_translation_cache_init(struct kvm *kvm);
void vgic_lpi_translation_cache_destroy(struct kvm *kvm);
void vgic_its_invalidate_cache(struct kvm *kvm);

+/* GICv4.1 MMIO interface */
+int vgic_its_inv_lpi(struct kvm *kvm, struct vgic_irq *irq);
+int vgic_its_invall(struct kvm_vcpu *vcpu);
+
bool vgic_supports_direct_msis(struct kvm *kvm);
int vgic_v4_init(struct kvm *kvm);
void vgic_v4_teardown(struct kvm *kvm);
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index bb30a6803d9f..d54bb44d6d98 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -344,6 +344,7 @@ struct vgic_cpu {
struct vgic_io_device rd_iodev;
struct vgic_redist_region *rdreg;
u32 rdreg_index;
+ atomic_t syncr_busy;

/* Contains the attributes and gpa of the LPI pending tables. */
u64 pendbaser;
--
2.34.1