smccc/kvm_guest: Enable errata based on implementation CPUs

Retrieve any migration target implementation CPUs using the hypercall
and enable associated errata.

Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Sebastian Ott <sebott@redhat.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20250221140229.12588-6-shameerali.kolothum.thodi@huawei.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

1 files changed, 64 insertions, 0 deletions

diff --git a/drivers/firmware/smccc/kvm_guest.c b/drivers/firmware/smccc/kvm_guest.c
index f3319be20b36..2f03b582c298 100644
--- a/drivers/firmware/smccc/kvm_guest.c
+++ b/drivers/firmware/smccc/kvm_guest.c
@@ -6,8 +6,11 @@
 #include <linux/bitmap.h>
 #include <linux/cache.h>
 #include <linux/kernel.h>
+#include <linux/memblock.h>
 #include <linux/string.h>
 
+#include <uapi/linux/psci.h>
+
 #include <asm/hypervisor.h>
 
 static DECLARE_BITMAP(__kvm_arm_hyp_services, ARM_SMCCC_KVM_NUM_FUNCS) __ro_after_init = { };
@@ -51,3 +54,64 @@ bool kvm_arm_hyp_service_available(u32 func_id)
 	return test_bit(func_id, __kvm_arm_hyp_services);
 }
 EXPORT_SYMBOL_GPL(kvm_arm_hyp_service_available);
+
+void  __init kvm_arm_target_impl_cpu_init(void)
+{
+	int i;
+	u32 ver;
+	u64 max_cpus;
+	struct arm_smccc_res res;
+	struct target_impl_cpu *target;
+
+	if (!kvm_arm_hyp_service_available(ARM_SMCCC_KVM_FUNC_DISCOVER_IMPL_VER) ||
+	    !kvm_arm_hyp_service_available(ARM_SMCCC_KVM_FUNC_DISCOVER_IMPL_CPUS))
+		return;
+
+	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_DISCOVER_IMPL_VER_FUNC_ID,
+			     0, &res);
+	if (res.a0 != SMCCC_RET_SUCCESS)
+		return;
+
+	/* Version info is in lower 32 bits and is in SMMCCC_VERSION format */
+	ver = lower_32_bits(res.a1);
+	if (PSCI_VERSION_MAJOR(ver) != 1) {
+		pr_warn("Unsupported target CPU implementation version v%d.%d\n",
+			PSCI_VERSION_MAJOR(ver), PSCI_VERSION_MINOR(ver));
+		return;
+	}
+
+	if (!res.a2) {
+		pr_warn("No target implementation CPUs specified\n");
+		return;
+	}
+
+	max_cpus = res.a2;
+	target = memblock_alloc(sizeof(*target) * max_cpus,  __alignof__(*target));
+	if (!target) {
+		pr_warn("Not enough memory for struct target_impl_cpu\n");
+		return;
+	}
+
+	for (i = 0; i < max_cpus; i++) {
+		arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_DISCOVER_IMPL_CPUS_FUNC_ID,
+				     i, &res);
+		if (res.a0 != SMCCC_RET_SUCCESS) {
+			pr_warn("Discovering target implementation CPUs failed\n");
+			goto mem_free;
+		}
+		target[i].midr = res.a1;
+		target[i].revidr = res.a2;
+		target[i].aidr = res.a3;
+	};
+
+	if (!cpu_errata_set_target_impl(max_cpus, target)) {
+		pr_warn("Failed to set target implementation CPUs\n");
+		goto mem_free;
+	}
+
+	pr_info("Number of target implementation CPUs is %lld\n", max_cpus);
+	return;
+
+mem_free:
+	memblock_free(target, sizeof(*target) * max_cpus);
+}