[PATCH v2 07/25] KVM: arm64: vgic-v3: Add ICV_IAR1_EL1 handler

Marc Zyngier
2017-06-01T10:20:59Z

Add a handler for reading the guest's view of the ICC_IAR1_EL1
register. This involves finding the highest priority Group-1
interrupt, checking against both PMR and the active group
priority, activating the interrupt and setting the group
priority as active.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
include/linux/irqchip/arm-gic-v3.h | 1 +
virt/kvm/arm/hyp/vgic-v3-sr.c | 150 +++++++++++++++++++++++++++++++++++++
2 files changed, 151 insertions(+)

diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index fffb91202bc9..401db585a534 100644
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -405,6 +405,7 @@
#define ICH_LR_PHYS_ID_SHIFT 32
#define ICH_LR_PHYS_ID_MASK (0x3ffULL << ICH_LR_PHYS_ID_SHIFT)
#define ICH_LR_PRIORITY_SHIFT 48
+#define ICH_LR_PRIORITY_MASK (0xffULL << ICH_LR_PRIORITY_SHIFT)

/* These are for GICv2 emulation only */
#define GICH_LR_VIRTUALID (0x3ffUL << 0)
diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c
index 168539dfd0b9..16a2eadc7a5c 100644
--- a/virt/kvm/arm/hyp/vgic-v3-sr.c
+++ b/virt/kvm/arm/hyp/vgic-v3-sr.c
@@ -24,6 +24,7 @@

#define vtr_to_max_lr_idx(v) ((v) & 0xf)
#define vtr_to_nr_pre_bits(v) (((u32)(v) >> 26) + 1)
+#define vtr_to_nr_apr_regs(v) (1 << (vtr_to_nr_pre_bits(v) - 5))

static u64 __hyp_text __gic_v3_get_lr(unsigned int lr)
{
@@ -375,6 +376,79 @@ void __hyp_text __vgic_v3_write_vmcr(u32 vmcr)

#ifdef CONFIG_ARM64

+static int __hyp_text __vgic_v3_get_group(struct kvm_vcpu *vcpu)
+{
+ u32 esr = kvm_vcpu_get_hsr(vcpu);
+ u8 crm = (esr & ESR_ELx_SYS64_ISS_CRM_MASK) >> ESR_ELx_SYS64_ISS_CRM_SHIFT;
+
+ return crm != 8;
+}
+
+#define GICv3_IDLE_PRIORITY 0xff
+
+static int __hyp_text __vgic_v3_highest_priority_lr(struct kvm_vcpu *vcpu,
+ u32 vmcr,
+ u64 *lr_val)
+{
+ unsigned int used_lrs = vcpu->arch.vgic_cpu.used_lrs;
+ u8 priority = GICv3_IDLE_PRIORITY;
+ int i, lr = -1;
+
+ for (i = 0; i < used_lrs; i++) {
+ u64 val = __gic_v3_get_lr(i);
+ u8 lr_prio = (val & ICH_LR_PRIORITY_MASK) >> ICH_LR_PRIORITY_SHIFT;
+
+ /* Not pending in the state? */
+ if ((val & ICH_LR_STATE) != ICH_LR_PENDING_BIT)
+ continue;
+
+ /* Group-0 interrupt, but Group-0 disabled? */
+ if (!(val & ICH_LR_GROUP) && !(vmcr & ICH_VMCR_ENG0_MASK))
+ continue;
+
+ /* Group-1 interrupt, but Group-1 disabled? */
+ if ((val & ICH_LR_GROUP) && !(vmcr & ICH_VMCR_ENG1_MASK))
+ continue;
+
+ /* Not the highest priority? */
+ if (lr_prio >= priority)
+ continue;
+
+ /* This is a candidate */
+ priority = lr_prio;
+ *lr_val = val;
+ lr = i;
+ }
+
+ if (lr == -1)
+ *lr_val = ICC_IAR1_EL1_SPURIOUS;
+
+ return lr;
+}
+
+static int __hyp_text __vgic_v3_get_highest_active_priority(void)
+{
+ u8 nr_pre_bits = vtr_to_nr_pre_bits(read_gicreg(ICH_VTR_EL2));
+ u8 nr_apr_regs = vtr_to_nr_apr_regs(read_gicreg(ICH_VTR_EL2));
+ u32 hap = 0;
+ int i;
+
+ for (i = 0; i < nr_apr_regs; i++) {
+ u32 val;
+
+ val = __vgic_v3_read_ap0rn(i);
+ val |= __vgic_v3_read_ap1rn(i);
+ if (!val) {
+ hap += 32;
+ continue;
+ }
+
+ return (hap + __ffs(val)) << (8 - nr_pre_bits);
+ }
+
+ return GICv3_IDLE_PRIORITY;
+}
+
static unsigned int __hyp_text __vgic_v3_get_bpr0(u32 vmcr)
{
return (vmcr & ICH_VMCR_BPR0_MASK) >> ICH_VMCR_BPR0_SHIFT;
@@ -395,6 +469,79 @@ static unsigned int __hyp_text __vgic_v3_get_bpr1(u32 vmcr)
return bpr;
}

+/*
+ * Convert a priority to a preemption level, taking the relevant BPR
+ * into account by zeroing the sub-priority bits.
+ */
+static u8 __hyp_text __vgic_v3_pri_to_pre(u8 pri, u32 vmcr, int grp)
+{
+ unsigned int bpr;
+
+ if (!grp)
+ bpr = __vgic_v3_get_bpr0(vmcr) + 1;
+ else
+ bpr = __vgic_v3_get_bpr1(vmcr);
+
+ return pri & (GENMASK(7, 0) << bpr);
+}
+
+/*
+ * The priority value is independent of any of the BPR values, so we
+ * normalize it using nr_pre_bits. This guarantees that no matter what
+ * the guest does with its BPR, we can always set/get the same value
+ * of a priority.
+ */
+static void __hyp_text __vgic_v3_set_active_priority(u8 pri, u32 vmcr, int grp)
+{
+ u8 nr_pre_bits, pre, ap;
+ u32 val;
+ int apr;
+
+ nr_pre_bits = vtr_to_nr_pre_bits(read_gicreg(ICH_VTR_EL2));
+ pre = __vgic_v3_pri_to_pre(pri, vmcr, grp);
+ ap = pre >> (8 - nr_pre_bits);
+ apr = ap / 32;
+
+ val = __vgic_v3_read_ap1rn(apr);
+ __vgic_v3_write_ap1rn(val | BIT(ap % 32), apr);
+}
+
+static void __hyp_text __vgic_v3_read_iar(struct kvm_vcpu *vcpu, u32 vmcr, int rt)
+{
+ u64 lr_val;
+ u8 lr_prio, pmr;
+ int lr, grp;
+
+ grp = __vgic_v3_get_group(vcpu);
+
+ lr = __vgic_v3_highest_priority_lr(vcpu, vmcr, &lr_val);
+ if (lr < 0)
+ goto spurious;
+
+ if (grp != !!(lr_val & ICH_LR_GROUP))
+ goto spurious;
+
+ pmr = (vmcr & ICH_VMCR_PMR_MASK) >> ICH_VMCR_PMR_SHIFT;
+ lr_prio = (lr_val & ICH_LR_PRIORITY_MASK) >> ICH_LR_PRIORITY_SHIFT;
+ if (pmr <= lr_prio)
+ goto spurious;
+
+ if (__vgic_v3_get_highest_active_priority() <= lr_prio)
+ goto spurious;
+
+ lr_val &= ~ICH_LR_STATE;
+ /* No active state for LPIs */
+ if ((lr_val & ICH_LR_VIRTUAL_ID_MASK) <= VGIC_MAX_SPI)
+ lr_val |= ICH_LR_ACTIVE_BIT;
+ __gic_v3_set_lr(lr_val, lr);
+ __vgic_v3_set_active_priority(lr_prio, vmcr, grp);
+ vcpu_set_reg(vcpu, rt, lr_val & ICH_LR_VIRTUAL_ID_MASK);
+ return;
+
+spurious:
+ vcpu_set_reg(vcpu, rt, ICC_IAR1_EL1_SPURIOUS);
+}
+
static void __hyp_text __vgic_v3_read_igrpen1(struct kvm_vcpu *vcpu, u32 vmcr, int rt)
{
vcpu_set_reg(vcpu, rt, !!(vmcr & ICH_VMCR_ENG1_MASK));
@@ -459,6 +606,9 @@ int __hyp_text __vgic_v3_perform_cpuif_access(struct kvm_vcpu *vcpu)
is_read = (esr & ESR_ELx_SYS64_ISS_DIR_MASK) == ESR_ELx_SYS64_ISS_DIR_READ;

switch (sysreg) {
+ case SYS_ICC_IAR1_EL1:
+ fn = __vgic_v3_read_iar;
+ break;
case SYS_ICC_GRPEN1_EL1:
if (is_read)
fn = __vgic_v3_read_igrpen1;
--
2.11.0