[PATCH v4 17/19] arm64: KVM: add SGI generation register emulation
Andre Przywara
andre.przywara at arm.com
Fri Nov 14 02:08:01 PST 2014
While the generation of a (virtual) inter-processor interrupt (SGI)
on a GICv2 works by writing to a MMIO register, GICv3 uses the system
register ICC_SGI1R_EL1 to trigger them.
Trap that register on ARM64 hosts and handle it in a new handler
function in the GICv3 emulation code.
Signed-off-by: Andre Przywara <andre.przywara at arm.com>
---
Changelog v3...v4:
- moved addition of vgic_v3_dispatch_sgi() from earlier patch into here
- move MPIDR comparison into extra function
- use new ICC_SGI1R_ field names
- improve readability of vgic_v3_dispatch_sgi()
- add and refine comments
arch/arm64/kvm/sys_regs.c | 26 ++++++++++
include/kvm/arm_vgic.h | 1 +
virt/kvm/arm/vgic-v3-emul.c | 113 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 140 insertions(+)
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index fd3ffc3..e59369a 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -165,6 +165,27 @@ static bool access_sctlr(struct kvm_vcpu *vcpu,
return true;
}
+/*
+ * Trap handler for the GICv3 SGI generation system register.
+ * Forward the request to the VGIC emulation.
+ * The cp15_64 code makes sure this automatically works
+ * for both AArch64 and AArch32 accesses.
+ */
+static bool access_gic_sgi(struct kvm_vcpu *vcpu,
+ const struct sys_reg_params *p,
+ const struct sys_reg_desc *r)
+{
+ u64 val;
+
+ if (!p->is_write)
+ return read_from_write_only(vcpu, p);
+
+ val = *vcpu_reg(vcpu, p->Rt);
+ vgic_v3_dispatch_sgi(vcpu, val);
+
+ return true;
+}
+
static bool trap_raz_wi(struct kvm_vcpu *vcpu,
const struct sys_reg_params *p,
const struct sys_reg_desc *r)
@@ -431,6 +452,9 @@ static const struct sys_reg_desc sys_reg_descs[] = {
/* VBAR_EL1 */
{ Op0(0b11), Op1(0b000), CRn(0b1100), CRm(0b0000), Op2(0b000),
NULL, reset_val, VBAR_EL1, 0 },
+ /* ICC_SGI1R_EL1 */
+ { Op0(0b11), Op1(0b000), CRn(0b1100), CRm(0b1011), Op2(0b101),
+ access_gic_sgi },
/* CONTEXTIDR_EL1 */
{ Op0(0b11), Op1(0b000), CRn(0b1101), CRm(0b0000), Op2(0b001),
access_vm_reg, reset_val, CONTEXTIDR_EL1, 0 },
@@ -659,6 +683,8 @@ static const struct sys_reg_desc cp14_64_regs[] = {
* register).
*/
static const struct sys_reg_desc cp15_regs[] = {
+ { Op1( 0), CRn( 0), CRm(12), Op2( 0), access_gic_sgi },
+
{ Op1( 0), CRn( 1), CRm( 0), Op2( 0), access_sctlr, NULL, c1_SCTLR },
{ Op1( 0), CRn( 2), CRm( 0), Op2( 0), access_vm_reg, NULL, c2_TTBR0 },
{ Op1( 0), CRn( 2), CRm( 0), Op2( 1), access_vm_reg, NULL, c2_TTBR1 },
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index c1ef5a9..357a935 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -305,6 +305,7 @@ void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu);
void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu);
int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int irq_num,
bool level);
+void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg);
int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu);
bool vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
struct kvm_exit_mmio *mmio);
diff --git a/virt/kvm/arm/vgic-v3-emul.c b/virt/kvm/arm/vgic-v3-emul.c
index 97b5801..58d7457 100644
--- a/virt/kvm/arm/vgic-v3-emul.c
+++ b/virt/kvm/arm/vgic-v3-emul.c
@@ -828,6 +828,119 @@ int vgic_v3_init_emulation(struct kvm *kvm)
return 0;
}
+/*
+ * Compare a given affinity (level 1-3 and a level 0 mask, from the SGI
+ * generation register ICC_SGI1R_EL1) with a given VCPU.
+ * If the VCPU's MPIDR matches, return the level0 affinity, otherwise
+ * return -1.
+ */
+static int match_mpidr(u64 sgi_aff, u16 sgi_cpu_mask, struct kvm_vcpu *vcpu)
+{
+ unsigned long affinity;
+ int level0;
+
+ /*
+ * Split the current VCPU's MPIDR into affinity level 0 and the
+ * rest as this is what we have to compare against.
+ */
+ affinity = kvm_vcpu_get_mpidr_aff(vcpu);
+ level0 = MPIDR_AFFINITY_LEVEL(affinity, 0);
+ affinity &= ~MPIDR_LEVEL_MASK;
+
+ /* bail out if the upper three levels don't match */
+ if (sgi_aff != affinity)
+ return -1;
+
+ /* Is this VCPU's bit set in the mask ? */
+ if (!(sgi_cpu_mask & BIT(level0)))
+ return -1;
+
+ return level0;
+}
+
+#define SGI_AFFINITY_LEVEL(reg, level) \
+ ((((reg) & ICC_SGI1R_AFFINITY_## level ##_MASK) \
+ >> ICC_SGI1R_AFFINITY_## level ##_SHIFT) << MPIDR_LEVEL_SHIFT(level))
+
+/**
+ * vgic_v3_dispatch_sgi - handle SGI requests from VCPUs
+ * @vcpu: The VCPU requesting a SGI
+ * @reg: The value written into the ICC_SGI1R_EL1 register by that VCPU
+ *
+ * With GICv3 (and ARE=1) CPUs trigger SGIs by writing to an architectural
+ * system register. This will trap in sys_regs.c and call this function.
+ * This ICC_SGI1R_EL1 register contains the upper three affinity levels of the
+ * target processors as well as a bitmask of 16 Aff0 CPUs.
+ * If the interrupt routing mode bit is not set, we iterate over all VCPUs to
+ * check for matching ones. If this bit is set, we signal all, but not the
+ * calling VCPU.
+ */
+void vgic_v3_dispatch_sgi(struct kvm_vcpu *vcpu, u64 reg)
+{
+ struct kvm *kvm = vcpu->kvm;
+ struct kvm_vcpu *c_vcpu;
+ struct vgic_dist *dist = &kvm->arch.vgic;
+ u16 target_cpus;
+ u64 mpidr;
+ int sgi, c, vcpu_id;
+ bool broadcast;
+ int updated = 0;
+
+ vcpu_id = vcpu->vcpu_id;
+
+ sgi = (reg & ICC_SGI1R_SGI_ID_MASK) >> ICC_SGI1R_SGI_ID_SHIFT;
+ broadcast = reg & BIT(ICC_SGI1R_IRQ_ROUTING_MODE_BIT);
+ target_cpus = (reg & ICC_SGI1R_TARGET_LIST_MASK) >> ICC_SGI1R_TARGET_LIST_SHIFT;
+ mpidr = SGI_AFFINITY_LEVEL(reg, 3);
+ mpidr |= SGI_AFFINITY_LEVEL(reg, 2);
+ mpidr |= SGI_AFFINITY_LEVEL(reg, 1);
+ mpidr &= ~MPIDR_LEVEL_MASK;
+
+ /*
+ * We take the dist lock here, because we come from the sysregs
+ * code path and not from the MMIO one (which already takes the lock).
+ */
+ spin_lock(&dist->lock);
+
+ /*
+ * We iterate over all VCPUs to find the MPIDRs matching the request.
+ * If we have handled one CPU, we clear it's bit to detect early
+ * if we are already finished. This avoids iterating through all
+ * VCPUs when most of the times we just signal a single VCPU.
+ */
+ kvm_for_each_vcpu(c, c_vcpu, kvm) {
+
+ /* Exit early if we have dealt with all requested CPUs */
+ if (!broadcast && target_cpus == 0)
+ break;
+
+ /* Don't signal the calling VCPU */
+ if (broadcast && c == vcpu_id)
+ continue;
+
+ if (!broadcast) {
+ int level0;
+
+ level0 = match_mpidr(mpidr, target_cpus, c_vcpu);
+ if (level0 == -1)
+ continue;
+
+ /* remove this matching VCPU from the mask */
+ target_cpus &= ~BIT(level0);
+ }
+
+ /* Flag the SGI as pending */
+ vgic_dist_irq_set_pending(c_vcpu, sgi);
+ updated = 1;
+ kvm_debug("SGI%d from CPU%d to CPU%d\n", sgi, vcpu_id, c);
+ }
+ if (updated)
+ vgic_update_state(vcpu->kvm);
+ spin_unlock(&dist->lock);
+ if (updated)
+ vgic_kick_vcpus(vcpu->kvm);
+}
+
static int vgic_v3_create(struct kvm_device *dev, u32 type)
{
return kvm_vgic_create(dev->kvm, type);
--
1.7.9.5
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