[PATCH v3 1/4] KVM: arm64: Disambiguate support for vSGIs v. vLPIs

Raghavendra Rao Ananta
2025-06-13T15:52:44Z

From: Oliver Upton <oliver.upton@linux.dev>

vgic_supports_direct_msis() is a bit of a misnomer, as it returns true
if either vSGIs or vLPIs are supported. Pick it apart into a few
predicates and replace some open-coded checks for vSGIs.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
arch/arm64/kvm/vgic/vgic-init.c | 4 ++--
arch/arm64/kvm/vgic/vgic-mmio-v3.c | 16 ++++++++++------
arch/arm64/kvm/vgic/vgic-v4.c | 4 ++--
arch/arm64/kvm/vgic/vgic.c | 4 ++--
arch/arm64/kvm/vgic/vgic.h | 7 +++++++
5 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index eb1205654ac8..5e0e4559004b 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -395,7 +395,7 @@ int vgic_init(struct kvm *kvm)
* v4 support so that we get HW-accelerated vSGIs. Otherwise, only
* enable it if we present a virtual ITS to the guest.
*/
- if (vgic_supports_direct_msis(kvm)) {
+ if (vgic_supports_direct_irqs(kvm)) {
ret = vgic_v4_init(kvm);
if (ret)
goto out;
@@ -443,7 +443,7 @@ static void kvm_vgic_dist_destroy(struct kvm *kvm)
dist->vgic_cpu_base = VGIC_ADDR_UNDEF;
}

- if (vgic_supports_direct_msis(kvm))
+ if (vgic_supports_direct_irqs(kvm))
vgic_v4_teardown(kvm);

xa_destroy(&dist->lpi_xa);
diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
index ae4c0593d114..1a9c5b4418b2 100644
--- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
@@ -50,8 +50,12 @@ bool vgic_has_its(struct kvm *kvm)

bool vgic_supports_direct_msis(struct kvm *kvm)
{
- return (kvm_vgic_global_state.has_gicv4_1 ||
- (kvm_vgic_global_state.has_gicv4 && vgic_has_its(kvm)));
+ return kvm_vgic_global_state.has_gicv4 && vgic_has_its(kvm);
+}
+
+bool vgic_supports_direct_sgis(struct kvm *kvm)
+{
+ return kvm_vgic_global_state.has_gicv4_1 && gic_cpuif_has_vsgi();
}

/*
@@ -86,7 +90,7 @@ static unsigned long vgic_mmio_read_v3_misc(struct kvm_vcpu *vcpu,
}
break;
case GICD_TYPER2:
- if (kvm_vgic_global_state.has_gicv4_1 && gic_cpuif_has_vsgi())
+ if (vgic_supports_direct_sgis(vcpu->kvm))
value = GICD_TYPER2_nASSGIcap;
break;
case GICD_IIDR:
@@ -119,7 +123,7 @@ static void vgic_mmio_write_v3_misc(struct kvm_vcpu *vcpu,
dist->enabled = val & GICD_CTLR_ENABLE_SS_G1;

/* Not a GICv4.1? No HW SGIs */
- if (!kvm_vgic_global_state.has_gicv4_1 || !gic_cpuif_has_vsgi())
+ if (!vgic_supports_direct_sgis(vcpu->kvm))
val &= ~GICD_CTLR_nASSGIreq;

/* Dist stays enabled? nASSGIreq is RO */
@@ -133,7 +137,7 @@ static void vgic_mmio_write_v3_misc(struct kvm_vcpu *vcpu,
if (is_hwsgi != dist->nassgireq)
vgic_v4_configure_vsgis(vcpu->kvm);

- if (kvm_vgic_global_state.has_gicv4_1 &&
+ if (vgic_supports_direct_sgis(vcpu->kvm) &&
was_enabled != dist->enabled)
kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_RELOAD_GICv4);
else if (!was_enabled && dist->enabled)
@@ -178,7 +182,7 @@ static int vgic_mmio_uaccess_write_v3_misc(struct kvm_vcpu *vcpu,
}
case GICD_CTLR:
/* Not a GICv4.1? No HW SGIs */
- if (!kvm_vgic_global_state.has_gicv4_1)
+ if (vgic_supports_direct_sgis(vcpu->kvm))
val &= ~GICD_CTLR_nASSGIreq;

dist->enabled = val & GICD_CTLR_ENABLE_SS_G1;
diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c
index 193946108192..e7e284d47a77 100644
--- a/arch/arm64/kvm/vgic/vgic-v4.c
+++ b/arch/arm64/kvm/vgic/vgic-v4.c
@@ -356,7 +356,7 @@ int vgic_v4_put(struct kvm_vcpu *vcpu)
{
struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;

- if (!vgic_supports_direct_msis(vcpu->kvm) || !vpe->resident)
+ if (!vgic_supports_direct_irqs(vcpu->kvm) || !vpe->resident)
return 0;

return its_make_vpe_non_resident(vpe, vgic_v4_want_doorbell(vcpu));
@@ -367,7 +367,7 @@ int vgic_v4_load(struct kvm_vcpu *vcpu)
struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
int err;

- if (!vgic_supports_direct_msis(vcpu->kvm) || vpe->resident)
+ if (!vgic_supports_direct_irqs(vcpu->kvm) || vpe->resident)
return 0;

if (vcpu_get_flag(vcpu, IN_WFI))
diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
index 8f8096d48925..f5148b38120a 100644
--- a/arch/arm64/kvm/vgic/vgic.c
+++ b/arch/arm64/kvm/vgic/vgic.c
@@ -951,7 +951,7 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
* can be directly injected (GICv4).
*/
if (list_empty(&vcpu->arch.vgic_cpu.ap_list_head) &&
- !vgic_supports_direct_msis(vcpu->kvm))
+ !vgic_supports_direct_irqs(vcpu->kvm))
return;

DEBUG_SPINLOCK_BUG_ON(!irqs_disabled());
@@ -965,7 +965,7 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
if (can_access_vgic_from_kernel())
vgic_restore_state(vcpu);

- if (vgic_supports_direct_msis(vcpu->kvm))
+ if (vgic_supports_direct_irqs(vcpu->kvm))
vgic_v4_commit(vcpu);
}

diff --git a/arch/arm64/kvm/vgic/vgic.h b/arch/arm64/kvm/vgic/vgic.h
index 4349084cb9a6..ebf9ed6adeac 100644
--- a/arch/arm64/kvm/vgic/vgic.h
+++ b/arch/arm64/kvm/vgic/vgic.h
@@ -370,6 +370,13 @@ 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);
+bool vgic_supports_direct_sgis(struct kvm *kvm);
+
+static inline bool vgic_supports_direct_irqs(struct kvm *kvm)
+{
+ return vgic_supports_direct_msis(kvm) || vgic_supports_direct_sgis(kvm);
+}
+
int vgic_v4_init(struct kvm *kvm);
void vgic_v4_teardown(struct kvm *kvm);
void vgic_v4_configure_vsgis(struct kvm *kvm);
--
2.50.0.rc2.692.g299adb8693-goog