linux-kernel - [PATCH kvmtool v4 12/15] arm64: psci: Implement AFFINITY

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250930103130.197534-14-suzuki.poulose@arm.com>
Date: Tue, 30 Sep 2025 11:31:27 +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 12/15] arm64: psci: Implement AFFINITY_INFO

From: Oliver Upton <oliver.upton@...ux.dev>

Implement support for PSCI AFFINITY_INFO by iteratively searching all of
the vCPUs in a VM for those that match the specified affinity. Pause the
VM to avoid racing against other PSCI calls in the system that might
change the power state of the vCPUs.

Signed-off-by: Oliver Upton <oliver.upton@...ux.dev>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 arm64/include/kvm/kvm-cpu-arch.h | 12 ++++++-
 arm64/psci.c                     | 59 ++++++++++++++++++++++++++++++++
 2 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/arm64/include/kvm/kvm-cpu-arch.h b/arm64/include/kvm/kvm-cpu-arch.h
index dbd90647..d9eb5f0e 100644
--- a/arm64/include/kvm/kvm-cpu-arch.h
+++ b/arm64/include/kvm/kvm-cpu-arch.h
@@ -7,7 +7,6 @@
 #include <pthread.h>
 #include <stdbool.h>
 
-#define ARM_MPIDR_HWID_BITMASK	0xFF00FFFFFFUL
 #define ARM_CPU_ID		3, 0, 0, 0
 #define ARM_CPU_ID_MPIDR	5
 #define ARM_CPU_CTRL		3, 0, 1, 0
@@ -67,6 +66,17 @@ unsigned long kvm_cpu__get_vcpu_mpidr(struct kvm_cpu *vcpu);
 int kvm_cpu__setup_pvtime(struct kvm_cpu *vcpu);
 int kvm_cpu__teardown_pvtime(struct kvm *kvm);
 
+#define ARM_MPIDR_HWID_BITMASK	0xFF00FFFFFFUL
+#define ARM_MPIDR_LEVEL_BITS_SHIFT	3
+#define ARM_MPIDR_LEVEL_BITS	(1 << ARM_MPIDR_LEVEL_BITS_SHIFT)
+#define ARM_MPIDR_LEVEL_MASK	((1 << ARM_MPIDR_LEVEL_BITS) - 1)
+
+#define ARM_MPIDR_LEVEL_SHIFT(level) \
+	(((1 << level) >> 1) << ARM_MPIDR_LEVEL_BITS_SHIFT)
+
+#define ARM_MPIDR_AFFINITY_LEVEL(mpidr, level) \
+	((mpidr >> ARM_MPIDR_LEVEL_SHIFT(level)) & ARM_MPIDR_LEVEL_MASK)
+
 static inline __u64 __core_reg_id(__u64 offset)
 {
 	__u64 id = KVM_REG_ARM64 | KVM_REG_ARM_CORE | offset;
diff --git a/arm64/psci.c b/arm64/psci.c
index 14c98639..94e39d40 100644
--- a/arm64/psci.c
+++ b/arm64/psci.c
@@ -6,6 +6,16 @@
 #include <linux/psci.h>
 #include <linux/types.h>
 
+#define AFFINITY_MASK(level)	~((0x1UL << ((level) * ARM_MPIDR_LEVEL_BITS)) - 1)
+
+static unsigned long psci_affinity_mask(unsigned long affinity_level)
+{
+	if (affinity_level <= 3)
+		return ARM_MPIDR_HWID_BITMASK & AFFINITY_MASK(affinity_level);
+
+	return 0;
+}
+
 static void psci_features(struct kvm_cpu *vcpu, struct arm_smccc_res *res)
 {
 	u32 arg = smccc_get_arg(vcpu, 1);
@@ -20,6 +30,8 @@ static void psci_features(struct kvm_cpu *vcpu, struct arm_smccc_res *res)
 	case PSCI_0_2_FN_CPU_OFF:
 	case PSCI_0_2_FN_CPU_ON:
 	case PSCI_0_2_FN64_CPU_ON:
+	case PSCI_0_2_FN_AFFINITY_INFO:
+	case PSCI_0_2_FN64_AFFINITY_INFO:
 	case ARM_SMCCC_VERSION_FUNC_ID:
 		res->a0 = PSCI_RET_SUCCESS;
 		break;
@@ -111,6 +123,49 @@ out_continue:
 	kvm__continue(vcpu->kvm);
 }
 
+static void affinity_info(struct kvm_cpu *vcpu, struct arm_smccc_res *res)
+{
+	u64 target_affinity = smccc_get_arg(vcpu, 1);
+	u64 lowest_level = smccc_get_arg(vcpu, 2);
+	u64 mpidr_mask = psci_affinity_mask(lowest_level);
+	struct kvm *kvm = vcpu->kvm;
+	bool matched = false;
+	int i;
+
+	if (!psci_valid_affinity(target_affinity) || lowest_level > 3) {
+		res->a0 = PSCI_RET_INVALID_PARAMS;
+		return;
+	}
+
+	kvm__pause(vcpu->kvm);
+
+	for (i = 0; i < kvm->nrcpus; i++) {
+		struct kvm_cpu *tmp = kvm->cpus[i];
+		u64 mpidr = kvm_cpu__get_vcpu_mpidr(tmp);
+		struct kvm_mp_state mp_state;
+
+		if ((mpidr & mpidr_mask) != target_affinity)
+			continue;
+
+		if (ioctl(tmp->vcpu_fd, KVM_GET_MP_STATE, &mp_state))
+			die_perror("KVM_GET_MP_STATE failed");
+
+		if (mp_state.mp_state != KVM_MP_STATE_STOPPED) {
+			res->a0 = PSCI_0_2_AFFINITY_LEVEL_ON;
+			goto out_continue;
+		}
+
+		matched = true;
+	}
+
+	if (matched)
+		res->a0 = PSCI_0_2_AFFINITY_LEVEL_OFF;
+	else
+		res->a0 = PSCI_RET_INVALID_PARAMS;
+out_continue:
+	kvm__continue(vcpu->kvm);
+}
+
 void handle_psci(struct kvm_cpu *vcpu, struct arm_smccc_res *res)
 {
 	switch (vcpu->kvm_run->hypercall.nr) {
@@ -131,6 +186,10 @@ void handle_psci(struct kvm_cpu *vcpu, struct arm_smccc_res *res)
 	case PSCI_0_2_FN64_CPU_ON:
 		cpu_on(vcpu, res);
 		break;
+	case PSCI_0_2_FN_AFFINITY_INFO:
+	case PSCI_0_2_FN64_AFFINITY_INFO:
+		affinity_info(vcpu, res);
+		break;
 	default:
 		res->a0 = PSCI_RET_NOT_SUPPORTED;
 	}
-- 
2.43.0