[PATCH v8 5/6] smccc/kvm_guest: Enable errata based on implementation CPUs

[Khushit Shah]

> On 21 Feb 2025, at 7:32 PM, Shameer Kolothum <shameerali.kolothum.thodi at huawei.com> wrote:
> 
> Retrieve any migration target implementation CPUs using the hypercall
> and enable associated errata.
> 
> Reviewed-by: Cornelia Huck <cohuck at redhat.com>
> Reviewed-by: Sebastian Ott <sebott at redhat.com>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
> ---
> arch/arm64/include/asm/cputype.h    |  7 ++++
> arch/arm64/include/asm/hypervisor.h |  1 +
> arch/arm64/kernel/cpu_errata.c      | 45 +++++++++++++++++---
> arch/arm64/kernel/cpufeature.c      |  2 +
> drivers/firmware/smccc/kvm_guest.c  | 64 +++++++++++++++++++++++++++++
> 5 files changed, 114 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
> index ccb4a155d118..cc2d58141be1 100644
> --- a/arch/arm64/include/asm/cputype.h
> +++ b/arch/arm64/include/asm/cputype.h
> @@ -276,6 +276,13 @@ static inline bool midr_is_cpu_model_range(u32 midr, u32 model, u32 rv_min,
> return _model == model && rv >= rv_min && rv <= rv_max;
> }
> 
> +struct target_impl_cpu {
> + u64 midr;
> + u64 revidr;
> + u64 aidr;
> +};
> +
> +bool cpu_errata_set_target_impl(u64 num, void *impl_cpus);
> bool is_midr_in_range_list(struct midr_range const *ranges);
> 
> static inline u64 __attribute_const__ read_cpuid_mpidr(void)
> diff --git a/arch/arm64/include/asm/hypervisor.h b/arch/arm64/include/asm/hypervisor.h
> index 409e239834d1..a12fd897c877 100644
> --- a/arch/arm64/include/asm/hypervisor.h
> +++ b/arch/arm64/include/asm/hypervisor.h
> @@ -6,6 +6,7 @@
> 
> void kvm_init_hyp_services(void);
> bool kvm_arm_hyp_service_available(u32 func_id);
> +void kvm_arm_target_impl_cpu_init(void);
> 
> #ifdef CONFIG_ARM_PKVM_GUEST
> void pkvm_init_hyp_services(void);
> diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
> index 1f51cf6378c5..66869d81c3d5 100644
> --- a/arch/arm64/kernel/cpu_errata.c
> +++ b/arch/arm64/kernel/cpu_errata.c
> @@ -14,10 +14,34 @@
> #include <asm/kvm_asm.h>
> #include <asm/smp_plat.h>
> 
> +static u64 target_impl_cpu_num;
> +static struct target_impl_cpu *target_impl_cpus;
> +
> +bool cpu_errata_set_target_impl(u64 num, void *impl_cpus)
> +{
> + if (target_impl_cpu_num || !num || !impl_cpus)
> + return false;
> +
> + target_impl_cpu_num = num;
> + target_impl_cpus = impl_cpus;
> + return true;
> +}
> +
> static inline bool is_midr_in_range(struct midr_range const *range)
> {
> - return midr_is_cpu_model_range(read_cpuid_id(), range->model,
> -       range->rv_min, range->rv_max);
> + int i;
> +
> + if (!target_impl_cpu_num)
> + return midr_is_cpu_model_range(read_cpuid_id(), range->model,
> +       range->rv_min, range->rv_max);
> +
> + for (i = 0; i < target_impl_cpu_num; i++) {
> + if (midr_is_cpu_model_range(target_impl_cpus[i].midr,
> +    range->model,
> +    range->rv_min, range->rv_max))
> + return true;
> + }
> + return false;
> }
> 
> bool is_midr_in_range_list(struct midr_range const *ranges)
> @@ -47,9 +71,20 @@ __is_affected_midr_range(const struct arm64_cpu_capabilities *entry,
> static bool __maybe_unused
> is_affected_midr_range(const struct arm64_cpu_capabilities *entry, int scope)
> {
> - WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());
> - return __is_affected_midr_range(entry, read_cpuid_id(),
> - read_cpuid(REVIDR_EL1));
> + int i;
> +
> + if (!target_impl_cpu_num) {
> + WARN_ON(scope != SCOPE_LOCAL_CPU || preemptible());
> + return __is_affected_midr_range(entry, read_cpuid_id(),
> + read_cpuid(REVIDR_EL1));
> + }
> +
> + for (i = 0; i < target_impl_cpu_num; i++) {
> + if (__is_affected_midr_range(entry, target_impl_cpus[i].midr,
> +     target_impl_cpus[i].midr))
Typo? Shouldn't the second arg be target_impl_cpus[i].revidr?

> + return true;
> + }
> + return false;
> }
> 
> static bool __maybe_unused
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 72e876f37cd4..5c61d9d9f097 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -86,6 +86,7 @@
> #include <asm/kvm_host.h>
> #include <asm/mmu_context.h>
> #include <asm/mte.h>
> +#include <asm/hypervisor.h>
> #include <asm/processor.h>
> #include <asm/smp.h>
> #include <asm/sysreg.h>
> @@ -3679,6 +3680,7 @@ unsigned long cpu_get_elf_hwcap3(void)
> 
> static void __init setup_boot_cpu_capabilities(void)
> {
> + kvm_arm_target_impl_cpu_init();
> /*
> * The boot CPU's feature register values have been recorded. Detect
> * boot cpucaps and local cpucaps for the boot CPU, then enable and
> 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);
> +}
> -- 
> 2.47.0
> 
>