[PATCH 07/16] KVM: arm64: nv: Plumb handling of GICv3 EL2 accesses

Marc Zyngier
2024-12-17T15:14:05Z

Wire the handling of all GICv3 EL2 registers, and provide emulation
for all the non memory-backed registers (ICC_SRE_EL2, ICH_VTR_EL2,
ICH_MISR_EL2, ICH_ELRSR_EL2, and ICH_EISR_EL2).

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/kvm/Makefile | 2 +-
arch/arm64/kvm/sys_regs.c | 95 +++++++++++++++++++-
arch/arm64/kvm/vgic/vgic-v3-nested.c | 125 +++++++++++++++++++++++++++
include/kvm/arm_vgic.h | 4 +
4 files changed, 224 insertions(+), 2 deletions(-)
create mode 100644 arch/arm64/kvm/vgic/vgic-v3-nested.c

diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 3cf7adb2b5038..209bc76263f10 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -23,7 +23,7 @@ kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \
vgic/vgic-v3.o vgic/vgic-v4.o \
vgic/vgic-mmio.o vgic/vgic-mmio-v2.o \
vgic/vgic-mmio-v3.o vgic/vgic-kvm-device.o \
- vgic/vgic-its.o vgic/vgic-debug.o
+ vgic/vgic-its.o vgic/vgic-debug.o vgic/vgic-v3-nested.o

kvm-$(CONFIG_HW_PERF_EVENTS) += pmu-emul.o pmu.o
kvm-$(CONFIG_ARM64_PTR_AUTH) += pauth.o
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 83c6b4a07ef56..c6d09c25b2522 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -17,6 +17,7 @@
#include <linux/mm.h>
#include <linux/printk.h>
#include <linux/uaccess.h>
+#include <linux/irqchip/arm-gic-v3.h>

#include <asm/arm_pmuv3.h>
#include <asm/cacheflush.h>
@@ -531,7 +532,13 @@ static bool access_gic_sre(struct kvm_vcpu *vcpu,
if (p->is_write)
return ignore_write(vcpu, p);

- p->regval = vcpu->arch.vgic_cpu.vgic_v3.vgic_sre;
+ if (p->Op1 == 4) { /* ICC_SRE_EL2 */
+ p->regval = (ICC_SRE_EL2_ENABLE | ICC_SRE_EL2_SRE |
+ ICC_SRE_EL1_DIB | ICC_SRE_EL1_DFB);
+ } else { /* ICC_SRE_EL1 */
+ p->regval = vcpu->arch.vgic_cpu.vgic_v3.vgic_sre;
+ }
+
return true;
}

@@ -2402,6 +2409,59 @@ static bool access_zcr_el2(struct kvm_vcpu *vcpu,
vq = SYS_FIELD_GET(ZCR_ELx, LEN, p->regval) + 1;
vq = min(vq, vcpu_sve_max_vq(vcpu));
vcpu_write_sys_reg(vcpu, vq - 1, ZCR_EL2);
+
+ return true;
+}
+
+static bool access_gic_vtr(struct kvm_vcpu *vcpu,
+ struct sys_reg_params *p,
+ const struct sys_reg_desc *r)
+{
+ if (p->is_write)
+ return write_to_read_only(vcpu, p, r);
+
+ p->regval = kvm_vgic_global_state.ich_vtr_el2;
+ p->regval &= ~(ICH_VTR_EL2_DVIM |
+ ICH_VTR_EL2_A3V |
+ ICH_VTR_EL2_IDbits);
+ p->regval |= ICH_VTR_EL2_nV4;
+
+ return true;
+}
+
+static bool access_gic_misr(struct kvm_vcpu *vcpu,
+ struct sys_reg_params *p,
+ const struct sys_reg_desc *r)
+{
+ if (p->is_write)
+ return write_to_read_only(vcpu, p, r);
+
+ p->regval = vgic_v3_get_misr(vcpu);
+
+ return true;
+}
+
+static bool access_gic_eisr(struct kvm_vcpu *vcpu,
+ struct sys_reg_params *p,
+ const struct sys_reg_desc *r)
+{
+ if (p->is_write)
+ return write_to_read_only(vcpu, p, r);
+
+ p->regval = vgic_v3_get_eisr(vcpu);
+
+ return true;
+}
+
+static bool access_gic_elrsr(struct kvm_vcpu *vcpu,
+ struct sys_reg_params *p,
+ const struct sys_reg_desc *r)
+{
+ if (p->is_write)
+ return write_to_read_only(vcpu, p, r);
+
+ p->regval = vgic_v3_get_elrsr(vcpu);
+
return true;
}

@@ -3050,7 +3110,40 @@ static const struct sys_reg_desc sys_reg_descs[] = {
EL2_REG(RVBAR_EL2, access_rw, reset_val, 0),
{ SYS_DESC(SYS_RMR_EL2), undef_access },

+ EL2_REG_VNCR(ICH_AP0R0_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_AP0R1_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_AP0R2_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_AP0R3_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_AP1R0_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_AP1R1_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_AP1R2_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_AP1R3_EL2, reset_val, 0),
+
+ { SYS_DESC(SYS_ICC_SRE_EL2), access_gic_sre },
+
EL2_REG_VNCR(ICH_HCR_EL2, reset_val, 0),
+ { SYS_DESC(SYS_ICH_VTR_EL2), access_gic_vtr },
+ { SYS_DESC(SYS_ICH_MISR_EL2), access_gic_misr },
+ { SYS_DESC(SYS_ICH_EISR_EL2), access_gic_eisr },
+ { SYS_DESC(SYS_ICH_ELRSR_EL2), access_gic_elrsr },
+ EL2_REG_VNCR(ICH_VMCR_EL2, reset_val, 0),
+
+ EL2_REG_VNCR(ICH_LR0_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR1_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR2_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR3_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR4_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR5_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR6_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR7_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR8_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR9_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR10_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR11_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR12_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR13_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR14_EL2, reset_val, 0),
+ EL2_REG_VNCR(ICH_LR15_EL2, reset_val, 0),

EL2_REG(CONTEXTIDR_EL2, access_rw, reset_val, 0),
EL2_REG(TPIDR_EL2, access_rw, reset_val, 0),
diff --git a/arch/arm64/kvm/vgic/vgic-v3-nested.c b/arch/arm64/kvm/vgic/vgic-v3-nested.c
new file mode 100644
index 0000000000000..48bfd2f556a36
--- /dev/null
+++ b/arch/arm64/kvm/vgic/vgic-v3-nested.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/cpu.h>
+#include <linux/kvm.h>
+#include <linux/kvm_host.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+
+#include <kvm/arm_vgic.h>
+
+#include <asm/kvm_arm.h>
+#include <asm/kvm_emulate.h>
+#include <asm/kvm_nested.h>
+
+#include "vgic.h"
+
+#define ICH_LRN(n) (ICH_LR0_EL2 + (n))
+
+struct mi_state {
+ u16 eisr;
+ u16 elrsr;
+ bool pend;
+};
+
+/*
+ * Nesting GICv3 support
+ *
+ * System register emulation:
+ *
+ * We get two classes of registers:
+ *
+ * - those backed by memory (LRs, APRs, HCR, VMCR): L1 can freely access
+ * them, and L0 doesn't see a thing.
+ *
+ * - those that always trap (ELRSR, EISR, MISR): these are status registers
+ * that are built on the fly based on the in-memory state.
+ *
+ * Only L1 can access the ICH_*_EL2 registers. A non-NV L2 obviously cannot,
+ * and a NV L2 would either access the VNCR page provided by L1 (memory
+ * based registers), or see the access redirected to L1 (registers that
+ * trap) thanks to NV being set by L1.
+ */
+
+static bool lr_triggers_eoi(u64 lr)
+{
+ return !(lr & (ICH_LR_STATE | ICH_LR_HW)) && (lr & ICH_LR_EOI);
+}
+
+static void vgic_compute_mi_state(struct kvm_vcpu *vcpu, struct mi_state *mi_state)
+{
+ u16 eisr = 0, elrsr = 0;
+ bool pend = false;
+
+ for (int i = 0; i < kvm_vgic_global_state.nr_lr; i++) {
+ u64 lr = __vcpu_sys_reg(vcpu, ICH_LRN(i));
+
+ if (lr_triggers_eoi(lr))
+ eisr |= BIT(i);
+ if (!(lr & ICH_LR_STATE))
+ elrsr |= BIT(i);
+ pend |= (lr & ICH_LR_PENDING_BIT);
+ }
+
+ mi_state->eisr = eisr;
+ mi_state->elrsr = elrsr;
+ mi_state->pend = pend;
+}
+
+u16 vgic_v3_get_eisr(struct kvm_vcpu *vcpu)
+{
+ struct mi_state mi_state;
+
+ vgic_compute_mi_state(vcpu, &mi_state);
+ return mi_state.eisr;
+}
+
+u16 vgic_v3_get_elrsr(struct kvm_vcpu *vcpu)
+{
+ struct mi_state mi_state;
+
+ vgic_compute_mi_state(vcpu, &mi_state);
+ return mi_state.elrsr;
+}
+
+u64 vgic_v3_get_misr(struct kvm_vcpu *vcpu)
+{
+ struct mi_state mi_state;
+ u64 reg = 0, hcr, vmcr;
+
+ hcr = __vcpu_sys_reg(vcpu, ICH_HCR_EL2);
+ vmcr = __vcpu_sys_reg(vcpu, ICH_VMCR_EL2);
+
+ vgic_compute_mi_state(vcpu, &mi_state);
+
+ if (mi_state.eisr)
+ reg |= ICH_MISR_EL2_EOI;
+
+ if (__vcpu_sys_reg(vcpu, ICH_HCR_EL2) & ICH_HCR_EL2_UIE) {
+ int used_lrs = kvm_vgic_global_state.nr_lr;
+
+ used_lrs -= hweight16(mi_state.elrsr);
+ reg |= (used_lrs <= 1) ? ICH_MISR_EL2_U : 0;
+ }
+
+ if ((hcr & ICH_HCR_EL2_LRENPIE) && FIELD_GET(ICH_HCR_EL2_EOIcount_MASK, hcr))
+ reg |= ICH_MISR_EL2_LRENP;
+
+ if ((hcr & ICH_HCR_EL2_NPIE) && !mi_state.pend)
+ reg |= ICH_MISR_EL2_NP;
+
+ if ((hcr & ICH_HCR_EL2_VGrp0EIE) && (vmcr & ICH_VMCR_ENG0_MASK))
+ reg |= ICH_MISR_EL2_VGrp0E;
+
+ if ((hcr & ICH_HCR_EL2_VGrp0DIE) && !(vmcr & ICH_VMCR_ENG0_MASK))
+ reg |= ICH_MISR_EL2_VGrp0D;
+
+ if ((hcr & ICH_HCR_EL2_VGrp1EIE) && (vmcr & ICH_VMCR_ENG1_MASK))
+ reg |= ICH_MISR_EL2_VGrp1E;
+
+ if ((hcr & ICH_HCR_EL2_VGrp1DIE) && !(vmcr & ICH_VMCR_ENG1_MASK))
+ reg |= ICH_MISR_EL2_VGrp1D;
+
+ return reg;
+}
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index 3a8ccfda34d29..5017fcc71e604 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -389,6 +389,10 @@ int kvm_vgic_vcpu_pending_irq(struct kvm_vcpu *vcpu);
void kvm_vgic_load(struct kvm_vcpu *vcpu);
void kvm_vgic_put(struct kvm_vcpu *vcpu);

+u16 vgic_v3_get_eisr(struct kvm_vcpu *vcpu);
+u16 vgic_v3_get_elrsr(struct kvm_vcpu *vcpu);
+u64 vgic_v3_get_misr(struct kvm_vcpu *vcpu);
+
#define irqchip_in_kernel(k) (!!((k)->arch.vgic.in_kernel))
#define vgic_initialized(k) ((k)->arch.vgic.initialized)
#define vgic_ready(k) ((k)->arch.vgic.ready)
--
2.39.2