From: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
[ Upstream commit 830dcc9f9a7cd26a812522a26efaacf7df6fc365 ]
We expect all CPUs to be running at the same EL inside the kernel
with or without VHE enabled and we have strict checks to ensure
that any mismatch triggers a kernel panic. If VHE is enabled,
we use the feature based on the boot CPU and all other CPUs
should follow. This makes it a perfect candidate for a capability
based on the boot CPU, which should be matched by all the CPUs
(both when is ON and OFF). This saves us some not-so-pretty
hooks and special code, just for verifying the conflict.
The patch also makes the VHE capability entry depend on
CONFIG_ARM64_VHE.
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Reviewed-by: Dave Martin <dave.martin@xxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/include/asm/cpufeature.h | 6 +++++
arch/arm64/include/asm/virt.h | 6 -----
arch/arm64/kernel/cpufeature.c | 5 ++--
arch/arm64/kernel/smp.c | 38 ------------------------------------
4 files changed, 9 insertions(+), 46 deletions(-)
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -283,6 +283,12 @@ extern struct arm64_ftr_reg arm64_ftr_re
(ARM64_CPUCAP_SCOPE_LOCAL_CPU | \
ARM64_CPUCAP_OPTIONAL_FOR_LATE_CPU)
+/*
+ * CPU feature used early in the boot based on the boot CPU. All secondary
+ * CPUs must match the state of the capability as detected by the boot CPU.
+ */
+#define ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE ARM64_CPUCAP_SCOPE_BOOT_CPU
+
struct arm64_cpu_capabilities {
const char *desc;
u16 capability;
--- a/arch/arm64/include/asm/virt.h
+++ b/arch/arm64/include/asm/virt.h
@@ -102,12 +102,6 @@ static inline bool has_vhe(void)
return false;
}
-#ifdef CONFIG_ARM64_VHE
-extern void verify_cpu_run_el(void);
-#else
-static inline void verify_cpu_run_el(void) {}
-#endif
-
#endif /* __ASSEMBLY__ */
#endif /* ! __ASM__VIRT_H */
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -982,13 +982,15 @@ static const struct arm64_cpu_capabiliti
.matches = cpufeature_pan_not_uao,
},
#endif /* CONFIG_ARM64_PAN */
+#ifdef CONFIG_ARM64_VHE
{
.desc = "Virtualization Host Extensions",
.capability = ARM64_HAS_VIRT_HOST_EXTN,
- .type = ARM64_CPUCAP_SYSTEM_FEATURE,
+ .type = ARM64_CPUCAP_STRICT_BOOT_CPU_FEATURE,
.matches = runs_at_el2,
.cpu_enable = cpu_copy_el2regs,
},
+#endif /* CONFIG_ARM64_VHE */
{
.desc = "32-bit EL0 Support",
.capability = ARM64_HAS_32BIT_EL0,
@@ -1332,7 +1334,6 @@ static bool verify_local_cpu_caps(u16 sc
*/
static void check_early_cpu_features(void)
{
- verify_cpu_run_el();
verify_cpu_asid_bits();
/*
* Early features are used by the kernel already. If there
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -83,43 +83,6 @@ enum ipi_msg_type {
IPI_WAKEUP
};
-#ifdef CONFIG_ARM64_VHE
-
-/* Whether the boot CPU is running in HYP mode or not*/
-static bool boot_cpu_hyp_mode;
-
-static inline void save_boot_cpu_run_el(void)
-{
- boot_cpu_hyp_mode = is_kernel_in_hyp_mode();
-}
-
-static inline bool is_boot_cpu_in_hyp_mode(void)
-{
- return boot_cpu_hyp_mode;
-}
-
-/*
- * Verify that a secondary CPU is running the kernel at the same
- * EL as that of the boot CPU.
- */
-void verify_cpu_run_el(void)
-{
- bool in_el2 = is_kernel_in_hyp_mode();
- bool boot_cpu_el2 = is_boot_cpu_in_hyp_mode();
-
- if (in_el2 ^ boot_cpu_el2) {
- pr_crit("CPU%d: mismatched Exception Level(EL%d) with boot CPU(EL%d)\n",
- smp_processor_id(),
- in_el2 ? 2 : 1,
- boot_cpu_el2 ? 2 : 1);
- cpu_panic_kernel();
- }
-}
-
-#else
-static inline void save_boot_cpu_run_el(void) {}
-#endif
-
#ifdef CONFIG_HOTPLUG_CPU
static int op_cpu_kill(unsigned int cpu);
#else
@@ -448,7 +411,6 @@ void __init smp_prepare_boot_cpu(void)
*/
jump_label_init();
cpuinfo_store_boot_cpu();
- save_boot_cpu_run_el();
}
static u64 __init of_get_cpu_mpidr(struct device_node *dn)
