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 cpability
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.zyng...@arm.com>
Cc: Dave Martin <dave.mar...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com>
---
 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(-)

diff --git a/arch/arm64/include/asm/cpufeature.h 
b/arch/arm64/include/asm/cpufeature.h
index 2f5edefdff99..6a1280493f57 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -287,6 +287,12 @@ extern struct arm64_ftr_reg arm64_ftr_reg_ctrel0;
        (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;
diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
index c5f89442785c..9d1e24e030b3 100644
--- 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 */
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index e9e81aabfe91..006e95d46a4a 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1030,13 +1030,15 @@ static const struct arm64_cpu_capabilities 
arm64_features[] = {
                .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,
@@ -1402,7 +1404,6 @@ static bool verify_local_cpu_caps(u16 scope_mask)
  */
 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
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 5cef11450183..f3e2e3aec0b0 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -85,43 +85,6 @@ 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
@@ -447,7 +410,6 @@ 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)
-- 
2.14.3

Reply via email to