[RFC PATCH 5/6] arm64: Use hypercall to check for any migration related errata

[Shameer Kolothum]

We now have a hypercall to retrieve any migration related erratas
for Guest kernels. Use that and update system_cpucaps based on any
set errata.

Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
---
 arch/arm64/include/asm/paravirt.h |  4 ++++
 arch/arm64/kernel/cpufeature.c    | 27 +++++++++++++++++++++++++++
 arch/arm64/kernel/paravirt.c      | 18 ++++++++++++++++++
 3 files changed, 49 insertions(+)

diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
index 9aa193e0e8f2..f2cbf2c51acc 100644
--- a/arch/arm64/include/asm/paravirt.h
+++ b/arch/arm64/include/asm/paravirt.h
@@ -19,11 +19,15 @@ static inline u64 paravirt_steal_clock(int cpu)
 }
 
 int __init pv_time_init(void);
+int __init pv_update_migrn_errata(unsigned long *errata_map);
 
 #else
 
 #define pv_time_init() do {} while (0)
 
+static inline int pv_update_migrn_errata(unsigned long *errata_map)
+{ return -EINVAL; }
+
 #endif // CONFIG_PARAVIRT
 
 #endif
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 7b39b0a4aadd..829b9eccec09 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>
@@ -111,6 +112,8 @@ static struct arm64_cpu_capabilities const __ro_after_init *cpucap_ptrs[ARM64_NC
 
 DECLARE_BITMAP(boot_cpucaps, ARM64_NCAPS);
 
+DECLARE_BITMAP(migrn_safe_errata_map, ARM64_NCAPS);
+
 bool arm64_use_ng_mappings = false;
 EXPORT_SYMBOL(arm64_use_ng_mappings);
 
@@ -3189,6 +3192,29 @@ void arm_get_migrn_errata_map(void *target, unsigned long *errata_map)
 	}
 }
 
+static void update_migrn_errata(void)
+{
+	int i, j;
+	const struct arm64_cpu_capabilities *caps;
+	u16 scope = ARM64_CPUCAP_LOCAL_CPU_ERRATUM;
+
+	if (pv_update_migrn_errata(migrn_safe_errata_map))
+		return;
+
+	for_each_set_bit(i, migrn_safe_errata_map, ARM64_NCAPS) {
+		for (j = 0; j < ARM64_NCAPS; j++) {
+			caps = cpucap_ptrs[j];
+			if (!caps || !(caps->type & scope) ||
+			    caps->migration_safe_cap != i ||
+			    cpus_have_cap(caps->capability))
+				continue;
+			if (caps->desc && !caps->cpus)
+				pr_info("Updated with migration errata: %s\n", caps->desc);
+			__set_bit(caps->capability, system_cpucaps);
+		}
+	}
+}
+
 static void update_cpu_capabilities(u16 scope_mask)
 {
 	int i;
@@ -3566,6 +3592,7 @@ static void __init setup_system_capabilities(void)
 	 * cpucaps.
 	 */
 	update_cpu_capabilities(SCOPE_SYSTEM);
+	update_migrn_errata();
 	enable_cpu_capabilities(SCOPE_ALL & ~SCOPE_BOOT_CPU);
 	apply_alternatives_all();
 
diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
index aa718d6a9274..04b1930d0e9a 100644
--- a/arch/arm64/kernel/paravirt.c
+++ b/arch/arm64/kernel/paravirt.c
@@ -23,6 +23,7 @@
 #include <asm/paravirt.h>
 #include <asm/pvclock-abi.h>
 #include <asm/smp_plat.h>
+#include <asm/hypervisor.h>
 
 struct static_key paravirt_steal_enabled;
 struct static_key paravirt_steal_rq_enabled;
@@ -153,6 +154,23 @@ static bool __init has_pv_steal_clock(void)
 	return (res.a0 == SMCCC_RET_SUCCESS);
 }
 
+int __init pv_update_migrn_errata(unsigned long *errata_map)
+{
+	int ret;
+	struct arm_smccc_res res;
+
+	ret = kvm_arm_hyp_service_available(ARM_SMCCC_KVM_FUNC_MIGRN_ERRATA);
+	if (ret <= 0)
+		return -EOPNOTSUPP;
+
+	arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_KVM_MIGRN_ERRATA, &res);
+	if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
+		return -EINVAL;
+
+	bitmap_from_arr64(errata_map, &res, ARM64_NCAPS);
+	return 0;
+}
+
 int __init pv_time_init(void)
 {
 	int ret;
-- 
2.45.2