[PATCH v4 3/3] arm64: paravirt: Enable errata based on implementation CPUs
Marc Zyngier
maz at kernel.org
Thu Dec 19 02:04:22 PST 2024
On Wed, 18 Dec 2024 10:53:45 +0000,
Shameer Kolothum <shameerali.kolothum.thodi at huawei.com> wrote:
>
> Retrieve any migration target implementation CPUs using the hypercall
> and enable associated errata.
>
> 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 | 25 +++++++++++++++++++++++--
> arch/arm64/include/asm/paravirt.h | 3 +++
> arch/arm64/kernel/cpu_errata.c | 20 +++++++++++++++++---
> arch/arm64/kernel/cpufeature.c | 2 ++
> arch/arm64/kernel/image-vars.h | 2 ++
> arch/arm64/kernel/paravirt.c | 31 +++++++++++++++++++++++++++++++
> 6 files changed, 78 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
> index dcf0e1ce892d..019d1b7dae80 100644
> --- a/arch/arm64/include/asm/cputype.h
> +++ b/arch/arm64/include/asm/cputype.h
> @@ -265,6 +265,16 @@ struct midr_range {
> #define MIDR_REV(m, v, r) MIDR_RANGE(m, v, r, v, r)
> #define MIDR_ALL_VERSIONS(m) MIDR_RANGE(m, 0, 0, 0xf, 0xf)
>
> +#define MAX_TARGET_IMPL_CPUS 64
> +
> +struct target_impl_cpu {
> + u64 midr;
> + u64 revidr;
> +};
> +
> +extern u32 target_impl_cpu_num;
> +extern struct target_impl_cpu target_impl_cpus[];
> +
> static inline bool midr_is_cpu_model_range(u32 midr, u32 model, u32 rv_min,
> u32 rv_max)
> {
> @@ -276,8 +286,19 @@ static inline bool midr_is_cpu_model_range(u32 midr, u32 model, u32 rv_min,
>
> 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;
> }
>
> static inline bool
> diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
> index 9aa193e0e8f2..95f1c15bbb7d 100644
> --- a/arch/arm64/include/asm/paravirt.h
> +++ b/arch/arm64/include/asm/paravirt.h
> @@ -19,11 +19,14 @@ static inline u64 paravirt_steal_clock(int cpu)
> }
>
> int __init pv_time_init(void);
> +void __init pv_target_impl_cpu_init(void);
>
> #else
>
> #define pv_time_init() do {} while (0)
>
> +#define pv_target_impl_cpu_init() do {} while (0)
> +
> #endif // CONFIG_PARAVIRT
>
> #endif
> diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
> index 929685c00263..4055082ce69b 100644
> --- a/arch/arm64/kernel/cpu_errata.c
> +++ b/arch/arm64/kernel/cpu_errata.c
> @@ -14,6 +14,9 @@
> #include <asm/kvm_asm.h>
> #include <asm/smp_plat.h>
>
> +u32 target_impl_cpu_num;
> +struct target_impl_cpu target_impl_cpus[MAX_TARGET_IMPL_CPUS];
> +
> static bool __maybe_unused
> __is_affected_midr_range(const struct arm64_cpu_capabilities *entry,
> u32 midr, u32 revidr)
> @@ -32,9 +35,20 @@ __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))
> + return true;
> + }
> + return false;
> }
>
> static bool __maybe_unused
> diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> index 4cc4ae16b28d..d32c767bf189 100644
> --- a/arch/arm64/kernel/cpufeature.c
> +++ b/arch/arm64/kernel/cpufeature.c
> @@ -85,6 +85,7 @@
> #include <asm/kvm_host.h>
> #include <asm/mmu_context.h>
> #include <asm/mte.h>
> +#include <asm/paravirt.h>
> #include <asm/processor.h>
> #include <asm/smp.h>
> #include <asm/sysreg.h>
> @@ -3642,6 +3643,7 @@ unsigned long cpu_get_elf_hwcap3(void)
>
> static void __init setup_boot_cpu_capabilities(void)
> {
> + pv_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/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
> index 8f5422ed1b75..694e19709c46 100644
> --- a/arch/arm64/kernel/image-vars.h
> +++ b/arch/arm64/kernel/image-vars.h
> @@ -49,6 +49,8 @@ PROVIDE(__pi_arm64_sw_feature_override = arm64_sw_feature_override);
> PROVIDE(__pi_arm64_use_ng_mappings = arm64_use_ng_mappings);
> #ifdef CONFIG_CAVIUM_ERRATUM_27456
> PROVIDE(__pi_cavium_erratum_27456_cpus = cavium_erratum_27456_cpus);
> +PROVIDE(__pi_target_impl_cpu_num = target_impl_cpu_num);
> +PROVIDE(__pi_target_impl_cpus = target_impl_cpus);
> #endif
> PROVIDE(__pi__ctype = _ctype);
> PROVIDE(__pi_memstart_offset_seed = memstart_offset_seed);
> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
> index aa718d6a9274..95fc3aae4a27 100644
> --- a/arch/arm64/kernel/paravirt.c
> +++ b/arch/arm64/kernel/paravirt.c
> @@ -153,6 +153,37 @@ static bool __init has_pv_steal_clock(void)
> return (res.a0 == SMCCC_RET_SUCCESS);
> }
>
> +void __init pv_target_impl_cpu_init(void)
> +{
> + struct arm_smccc_res res;
> + int index = 0, max_idx = -1;
> +
> + /* Check we have already set targets */
> + if (target_impl_cpu_num)
> + return;
> +
> + do {
> + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_DISCOVER_IMPL_CPUS_FUNC_ID,
> + index, &res);
> + if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
> + return;
Can't you probe for this as part of the KVM guest services?
> +
> + if (max_idx < 0) {
> + /* res.a0 should have a valid maximum CPU implementation index */
> + if (res.a0 >= MAX_TARGET_IMPL_CPUS)
> + return;
> + max_idx = res.a0;
> + }
> +
> + target_impl_cpus[index].midr = res.a1;
> + target_impl_cpus[index].revidr = res.a2;
> + index++;
> + } while (index <= max_idx);
> +
> + target_impl_cpu_num = index;
> + pr_info("Number of target implementation CPUs is %d\n", target_impl_cpu_num);
> +}
> +
> int __init pv_time_init(void)
> {
> int ret;
Independent of this, I wonder what we should output in sysfs
(/sys/devices/system/cpu/cpu*/regs/identification/*).
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
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