[PATCH v3 1/2] arm64: Add hypervisor safe helper for checking constant capabilities
From: suzuki.poulose@arm.com (Suzuki K Poulose)
Date: 2016-11-08 13:56:50
Also in:
kvmarm, lkml
Subsystem:
arm generic interrupt controller drivers, arm64 port (aarch64 architecture), irqchip drivers, the rest · Maintainers:
Marc Zyngier, Catalin Marinas, Will Deacon, Thomas Gleixner, Linus Torvalds
The hypervisor may not have full access to the kernel data structures and hence cannot safely use cpus_have_cap() helper for checking the system capability. Add a safe helper for hypervisors to check a constant system capability, which *doesn't* fall back to checking the bitmap maintained by the kernel. With this, make the cpus_have_cap() only check the bitmask and force constant cap checks to use the new API for quicker checks. Cc: Robert Ritcher <redacted> Cc: Tirumalesh Chalamarla <redacted> Cc: Marc Zyngier <redacted> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <redacted> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> --- arch/arm64/include/asm/cpufeature.h | 19 ++++++++++++------- arch/arm64/kernel/cpufeature.c | 2 +- arch/arm64/kernel/process.c | 2 +- drivers/irqchip/irq-gic-v3.c | 13 +------------ 4 files changed, 15 insertions(+), 21 deletions(-)
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 0bc0b1d..9890d20 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h@@ -9,8 +9,6 @@ #ifndef __ASM_CPUFEATURE_H #define __ASM_CPUFEATURE_H -#include <linux/jump_label.h> - #include <asm/cpucaps.h> #include <asm/hwcap.h> #include <asm/sysreg.h>
@@ -27,6 +25,8 @@ #ifndef __ASSEMBLY__ +#include <linux/bug.h> +#include <linux/jump_label.h> #include <linux/kernel.h> /* CPU feature register tracking */
@@ -104,14 +104,19 @@ static inline bool cpu_have_feature(unsigned int num) return elf_hwcap & (1UL << num); } +/* System capability check for constant caps */ +static inline bool cpus_have_const_cap(int num) +{ + if (num >= ARM64_NCAPS) + return false; + return static_branch_unlikely(&cpu_hwcap_keys[num]); +} + static inline bool cpus_have_cap(unsigned int num) { if (num >= ARM64_NCAPS) return false; - if (__builtin_constant_p(num)) - return static_branch_unlikely(&cpu_hwcap_keys[num]); - else - return test_bit(num, cpu_hwcaps); + return test_bit(num, cpu_hwcaps); } static inline void cpus_set_cap(unsigned int num)
@@ -200,7 +205,7 @@ static inline bool cpu_supports_mixed_endian_el0(void) static inline bool system_supports_32bit_el0(void) { - return cpus_have_cap(ARM64_HAS_32BIT_EL0); + return cpus_have_const_cap(ARM64_HAS_32BIT_EL0); } static inline bool system_supports_mixed_endian_el0(void)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index c02504e..fc2bd19 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c@@ -1102,5 +1102,5 @@ void __init setup_cpu_features(void) static bool __maybe_unused cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int __unused) { - return (cpus_have_cap(ARM64_HAS_PAN) && !cpus_have_cap(ARM64_HAS_UAO)); + return (cpus_have_const_cap(ARM64_HAS_PAN) && !cpus_have_const_cap(ARM64_HAS_UAO)); }
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 01753cd..18354f3 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c@@ -282,7 +282,7 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start, memset(childregs, 0, sizeof(struct pt_regs)); childregs->pstate = PSR_MODE_EL1h; if (IS_ENABLED(CONFIG_ARM64_UAO) && - cpus_have_cap(ARM64_HAS_UAO)) + cpus_have_const_cap(ARM64_HAS_UAO)) childregs->pstate |= PSR_UAO_BIT; p->thread.cpu_context.x19 = stack_start; p->thread.cpu_context.x20 = stk_sz;
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 19d642e..26e1d7f 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c@@ -120,11 +120,10 @@ static void gic_redist_wait_for_rwp(void) } #ifdef CONFIG_ARM64 -static DEFINE_STATIC_KEY_FALSE(is_cavium_thunderx); static u64 __maybe_unused gic_read_iar(void) { - if (static_branch_unlikely(&is_cavium_thunderx)) + if (cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_23154)) return gic_read_iar_cavium_thunderx(); else return gic_read_iar_common();
@@ -905,14 +904,6 @@ static const struct irq_domain_ops partition_domain_ops = { .select = gic_irq_domain_select, }; -static void gicv3_enable_quirks(void) -{ -#ifdef CONFIG_ARM64 - if (cpus_have_cap(ARM64_WORKAROUND_CAVIUM_23154)) - static_branch_enable(&is_cavium_thunderx); -#endif -} - static int __init gic_init_bases(void __iomem *dist_base, struct redist_region *rdist_regs, u32 nr_redist_regions,
@@ -935,8 +926,6 @@ static int __init gic_init_bases(void __iomem *dist_base, gic_data.nr_redist_regions = nr_redist_regions; gic_data.redist_stride = redist_stride; - gicv3_enable_quirks(); - /* * Find out how many interrupts are supported. * The GIC only supports up to 1020 interrupt sources (SGI+PPI+SPI)
--
2.7.4