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Message-ID: <20250930103130.197534-11-suzuki.poulose@arm.com>
Date: Tue, 30 Sep 2025 11:31:24 +0100
From: Suzuki K Poulose <suzuki.poulose@....com>
To: kvmarm@...ts.linux.dev
Cc: kvm@...r.kernel.org,
linux-kernel@...r.kernel.org,
will@...nel.org,
oliver.upton@...ux.dev,
maz@...nel.org,
alexandru.elisei@....com,
aneesh.kumar@...nel.org,
steven.price@....com,
tabba@...gle.com,
Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH kvmtool v4 09/15] arm64: Add skeleton implementation for PSCI
From: Oliver Upton <oliver.upton@...ux.dev>
Add an extremely barebones implementation for handling PSCI, where the
only supported call is PSCI_VERSION.
Signed-off-by: Oliver Upton <oliver.upton@...ux.dev>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
Makefile | 2 ++
arm64/include/asm/smccc.h | 65 ++++++++++++++++++++++++++++++++++++
arm64/kvm-cpu.c | 19 ++++++++---
arm64/kvm.c | 3 ++
arm64/psci.c | 69 +++++++++++++++++++++++++++++++++++++++
arm64/smccc.c | 44 +++++++++++++++++++++++++
6 files changed, 197 insertions(+), 5 deletions(-)
create mode 100644 arm64/include/asm/smccc.h
create mode 100644 arm64/psci.c
create mode 100644 arm64/smccc.c
diff --git a/Makefile b/Makefile
index 60e551fd..1c0e7f55 100644
--- a/Makefile
+++ b/Makefile
@@ -181,6 +181,8 @@ ifeq ($(ARCH), arm64)
OBJS += arm64/arm-cpu.o
OBJS += arm64/pvtime.o
OBJS += arm64/pmu.o
+ OBJS += arm64/psci.o
+ OBJS += arm64/smccc.o
ARCH_INCLUDE := arm64/include
ARCH_WANT_LIBFDT := y
diff --git a/arm64/include/asm/smccc.h b/arm64/include/asm/smccc.h
new file mode 100644
index 00000000..c1be21a7
--- /dev/null
+++ b/arm64/include/asm/smccc.h
@@ -0,0 +1,65 @@
+#ifndef __ARM_SMCCC_H__
+#define __ARM_SMCCC_H__
+
+#include "kvm/kvm-cpu.h"
+
+#include <linux/arm-smccc.h>
+#include <linux/types.h>
+
+static inline bool smccc_is_64bit(struct kvm_cpu *vcpu)
+{
+ return ARM_SMCCC_IS_64(vcpu->kvm_run->hypercall.nr);
+}
+
+static inline bool smccc_calling_conv_allowed(struct kvm_cpu *vcpu, u32 fn)
+{
+ return !(vcpu->kvm->cfg.arch.aarch32_guest && ARM_SMCCC_IS_64(fn));
+}
+
+static inline u64 smccc_get_arg(struct kvm_cpu *vcpu, u8 arg)
+{
+ u64 val;
+ struct kvm_one_reg reg = {
+ .id = ARM64_CORE_REG(regs.regs[arg]),
+ .addr = (u64)&val,
+ };
+
+ if (ioctl(vcpu->vcpu_fd, KVM_GET_ONE_REG, ®))
+ die_perror("KVM_GET_ONE_REG failed");
+
+ if (!smccc_is_64bit(vcpu))
+ val = (u32)val;
+
+ return val;
+}
+
+static inline void smccc_return_result(struct kvm_cpu *vcpu, struct arm_smccc_res *res)
+{
+ unsigned long *vals = (unsigned long *)res;
+ unsigned long i;
+
+ /*
+ * The author was lazy and chose to abuse the layout of struct
+ * arm_smccc_res to write a loop set the retvals.
+ */
+ for (i = 0; i < sizeof(*res) / sizeof(unsigned long); i++) {
+ u64 val = vals[i];
+ struct kvm_one_reg reg = {
+ .id = ARM64_CORE_REG(regs.regs[i]),
+ .addr = (u64)&val,
+ };
+
+ if (!smccc_is_64bit(vcpu))
+ val = (u32)val;
+
+ if (ioctl(vcpu->vcpu_fd, KVM_SET_ONE_REG, ®))
+ die_perror("KVM_SET_ONE_REG failed");
+ }
+}
+
+bool handle_hypercall(struct kvm_cpu *vcpu);
+void handle_psci(struct kvm_cpu *vcpu, struct arm_smccc_res *res);
+
+void kvm__setup_smccc(struct kvm *kvm);
+
+#endif /* __ARM_SMCCC_H__ */
diff --git a/arm64/kvm-cpu.c b/arm64/kvm-cpu.c
index f8e08b5d..6cd058fa 100644
--- a/arm64/kvm-cpu.c
+++ b/arm64/kvm-cpu.c
@@ -1,6 +1,7 @@
#include "kvm/kvm.h"
#include "kvm/kvm-cpu.h"
#include "kvm/virtio.h"
+#include "asm/smccc.h"
#include <asm/ptrace.h>
#include <linux/bitops.h>
@@ -229,11 +230,6 @@ void kvm_cpu__delete(struct kvm_cpu *vcpu)
free(vcpu);
}
-bool kvm_cpu__handle_exit(struct kvm_cpu *vcpu)
-{
- return false;
-}
-
void kvm_cpu__show_page_tables(struct kvm_cpu *vcpu)
{
}
@@ -469,3 +465,16 @@ void kvm_cpu__show_registers(struct kvm_cpu *vcpu)
die("KVM_GET_ONE_REG failed (lr)");
dprintf(debug_fd, " LR: 0x%lx\n", data);
}
+
+bool kvm_cpu__handle_exit(struct kvm_cpu *vcpu)
+{
+ struct kvm_run *run = vcpu->kvm_run;
+
+ switch (run->exit_reason) {
+ case KVM_EXIT_HYPERCALL:
+ handle_hypercall(vcpu);
+ return true;
+ default:
+ return false;
+ }
+}
diff --git a/arm64/kvm.c b/arm64/kvm.c
index 41c47b13..56e4f149 100644
--- a/arm64/kvm.c
+++ b/arm64/kvm.c
@@ -7,6 +7,8 @@
#include "kvm/gic.h"
#include "kvm/kvm-cpu.h"
+#include "asm/smccc.h"
+
#include <linux/byteorder.h>
#include <linux/cpumask.h>
#include <linux/kernel.h>
@@ -127,6 +129,7 @@ void kvm__arch_init(struct kvm *kvm)
die("Failed to create virtual GIC");
kvm__arch_enable_mte(kvm);
+ kvm__setup_smccc(kvm);
}
diff --git a/arm64/psci.c b/arm64/psci.c
new file mode 100644
index 00000000..72429b36
--- /dev/null
+++ b/arm64/psci.c
@@ -0,0 +1,69 @@
+#include "asm/smccc.h"
+#include "kvm/kvm.h"
+#include "kvm/kvm-cpu.h"
+#include "kvm/util.h"
+
+#include <linux/psci.h>
+#include <linux/types.h>
+
+static void psci_features(struct kvm_cpu *vcpu, struct arm_smccc_res *res)
+{
+ u32 arg = smccc_get_arg(vcpu, 1);
+
+ res->a0 = PSCI_RET_NOT_SUPPORTED;
+ if (!smccc_calling_conv_allowed(vcpu, arg))
+ return;
+
+ switch (arg) {
+ case PSCI_0_2_FN_CPU_SUSPEND:
+ case PSCI_0_2_FN64_CPU_SUSPEND:
+ case PSCI_0_2_FN_CPU_OFF:
+ case ARM_SMCCC_VERSION_FUNC_ID:
+ res->a0 = PSCI_RET_SUCCESS;
+ break;
+ }
+}
+
+static void cpu_suspend(struct kvm_cpu *vcpu, struct arm_smccc_res *res)
+{
+ struct kvm_mp_state mp_state = {
+ .mp_state = KVM_MP_STATE_SUSPENDED,
+ };
+
+ /* Rely on in-kernel emulation of a 'suspended' (i.e. WFI) state. */
+ if (ioctl(vcpu->vcpu_fd, KVM_SET_MP_STATE, &mp_state))
+ die_perror("KVM_SET_MP_STATE failed");
+
+ res->a0 = PSCI_RET_SUCCESS;
+}
+
+static void cpu_off(struct kvm_cpu *vcpu, struct arm_smccc_res *res)
+{
+ struct kvm_mp_state mp_state = {
+ .mp_state = KVM_MP_STATE_STOPPED,
+ };
+
+ if (ioctl(vcpu->vcpu_fd, KVM_SET_MP_STATE, &mp_state))
+ die_perror("KVM_SET_MP_STATE failed");
+}
+
+void handle_psci(struct kvm_cpu *vcpu, struct arm_smccc_res *res)
+{
+ switch (vcpu->kvm_run->hypercall.nr) {
+ case PSCI_0_2_FN_PSCI_VERSION:
+ res->a0 = PSCI_VERSION(1, 0);
+ break;
+ case PSCI_1_0_FN_PSCI_FEATURES:
+ psci_features(vcpu, res);
+ break;
+ case PSCI_0_2_FN_CPU_SUSPEND:
+ case PSCI_0_2_FN64_CPU_SUSPEND:
+ cpu_suspend(vcpu, res);
+ break;
+ case PSCI_0_2_FN_CPU_OFF:
+ cpu_off(vcpu, res);
+ break;
+ default:
+ res->a0 = PSCI_RET_NOT_SUPPORTED;
+ }
+}
diff --git a/arm64/smccc.c b/arm64/smccc.c
new file mode 100644
index 00000000..ef986d8c
--- /dev/null
+++ b/arm64/smccc.c
@@ -0,0 +1,44 @@
+#include "asm/smccc.h"
+#include "kvm/kvm.h"
+#include "kvm/kvm-cpu.h"
+#include "kvm/util.h"
+
+#include <linux/types.h>
+
+static void handle_std_call(struct kvm_cpu *vcpu, struct arm_smccc_res *res)
+{
+ u32 fn = vcpu->kvm_run->hypercall.nr;
+
+ switch (ARM_SMCCC_FUNC_NUM(fn)) {
+ /* PSCI */
+ case 0x00 ... 0x1F:
+ handle_psci(vcpu, res);
+ break;
+ }
+}
+
+bool handle_hypercall(struct kvm_cpu *vcpu)
+{
+ u32 fn = vcpu->kvm_run->hypercall.nr;
+ struct arm_smccc_res res = {
+ .a0 = SMCCC_RET_NOT_SUPPORTED,
+ };
+
+ if (!smccc_calling_conv_allowed(vcpu, fn))
+ goto out;
+
+ switch (ARM_SMCCC_OWNER_NUM(fn)) {
+ case ARM_SMCCC_OWNER_STANDARD:
+ handle_std_call(vcpu, &res);
+ break;
+ }
+
+out:
+ smccc_return_result(vcpu, &res);
+ return true;
+}
+
+void kvm__setup_smccc(struct kvm *kvm)
+{
+
+}
--
2.43.0
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