[PATCH v5 20/23] KVM: arm64: GICv4.1: Plumb SGI implementation selection in the distributor

Marc Zyngier
2020-03-04T20:36:39Z

The GICv4.1 architecture gives the hypervisor the option to let
the guest choose whether it wants the good old SGIs with an
active state, or the new, HW-based ones that do not have one.

For this, plumb the configuration of SGIs into the GICv3 MMIO
handling, present the GICD_TYPER2.nASSGIcap to the guest,
and handle the GICD_CTLR.nASSGIreq setting.

In order to be able to deal with the restore of a guest, also
apply the GICD_CTLR.nASSGIreq setting at first run so that we
can move the restored SGIs to the HW if that's what the guest
had selected in a previous life.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
virt/kvm/arm/vgic/vgic-mmio-v3.c | 48 ++++++++++++++++++++++++++++++--
virt/kvm/arm/vgic/vgic-v3.c | 2 ++
2 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
index de89da76a379..442f3b8c2559 100644
--- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
+++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
@@ -3,6 +3,7 @@
* VGICv3 MMIO handling functions
*/

+#include <linux/bitfield.h>
#include <linux/irqchip/arm-gic-v3.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
@@ -70,6 +71,8 @@ static unsigned long vgic_mmio_read_v3_misc(struct kvm_vcpu *vcpu,
if (vgic->enabled)
value |= GICD_CTLR_ENABLE_SS_G1;
value |= GICD_CTLR_ARE_NS | GICD_CTLR_DS;
+ if (kvm_vgic_global_state.has_gicv4_1 && vgic->nassgireq)
+ value |= GICD_CTLR_nASSGIreq;
break;
case GICD_TYPER:
value = vgic->nr_spis + VGIC_NR_PRIVATE_IRQS;
@@ -81,6 +84,10 @@ static unsigned long vgic_mmio_read_v3_misc(struct kvm_vcpu *vcpu,
value |= (INTERRUPT_ID_BITS_SPIS - 1) << 19;
}
break;
+ case GICD_TYPER2:
+ if (kvm_vgic_global_state.has_gicv4_1)
+ value = GICD_TYPER2_nASSGIcap;
+ break;
case GICD_IIDR:
value = (PRODUCT_ID_KVM << GICD_IIDR_PRODUCT_ID_SHIFT) |
(vgic->implementation_rev << GICD_IIDR_REVISION_SHIFT) |
@@ -98,17 +105,43 @@ static void vgic_mmio_write_v3_misc(struct kvm_vcpu *vcpu,
unsigned long val)
{
struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
- bool was_enabled = dist->enabled;

switch (addr & 0x0c) {
- case GICD_CTLR:
+ case GICD_CTLR: {
+ bool was_enabled, is_hwsgi;
+
+ mutex_lock(&vcpu->kvm->lock);
+
+ was_enabled = dist->enabled;
+ is_hwsgi = dist->nassgireq;
+
dist->enabled = val & GICD_CTLR_ENABLE_SS_G1;

+ /* Not a GICv4.1? No HW SGIs */
+ if (!kvm_vgic_global_state.has_gicv4_1)
+ val &= ~GICD_CTLR_nASSGIreq;
+
+ /* Dist stays enabled? nASSGIreq is RO */
+ if (was_enabled && dist->enabled) {
+ val &= ~GICD_CTLR_nASSGIreq;
+ val |= FIELD_PREP(GICD_CTLR_nASSGIreq, is_hwsgi);
+ }
+
+ /* Switching HW SGIs? */
+ dist->nassgireq = val & GICD_CTLR_nASSGIreq;
+ if (is_hwsgi != dist->nassgireq)
+ vgic_v4_configure_vsgis(vcpu->kvm);
+
if (!was_enabled && dist->enabled)
vgic_kick_vcpus(vcpu->kvm);
+
+ mutex_unlock(&vcpu->kvm->lock);
break;
+ }
case GICD_TYPER:
+ case GICD_TYPER2:
case GICD_IIDR:
+ /* This is at best for documentation purposes... */
return;
}
}
@@ -117,10 +150,21 @@ static int vgic_mmio_uaccess_write_v3_misc(struct kvm_vcpu *vcpu,
gpa_t addr, unsigned int len,
unsigned long val)
{
+ struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
+
switch (addr & 0x0c) {
case GICD_IIDR:
if (val != vgic_mmio_read_v3_misc(vcpu, addr, len))
return -EINVAL;
+ return 0;
+ case GICD_CTLR:
+ /* Not a GICv4.1? No HW SGIs */
+ if (!kvm_vgic_global_state.has_gicv4_1)
+ val &= ~GICD_CTLR_nASSGIreq;
+
+ dist->enabled = val & GICD_CTLR_ENABLE_SS_G1;
+ dist->nassgireq = val & GICD_CTLR_nASSGIreq;
+ return 0;
}

vgic_mmio_write_v3_misc(vcpu, addr, len, val);
diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index 1bc09b523486..2c9fc13e2c59 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -540,6 +540,8 @@ int vgic_v3_map_resources(struct kvm *kvm)
goto out;
}

+ if (kvm_vgic_global_state.has_gicv4_1)
+ vgic_v4_configure_vsgis(kvm);
dist->ready = true;

out:
--
2.20.1