[PATCH 3/3] arm64: cpufeature: upgrade hyp caps to final
Mark Rutland
mark.rutland at arm.com
Wed Oct 7 08:52:11 EDT 2020
We finalize caps before initializing kvm hyp code, and any use of
cpus_have_const_cap() in kvm hyp code generates redundant and
potentially unsound code to read the cpu_hwcaps array.
A number of helper functions used in both hyp context and regular kernel
context use cpus_have_const_cap(), as some regular kernel code runs
before the capabilities are finalized. It's tedious and error-prone to
write separate copies of these for hyp and non-hyp code.
So that we can avoid the redundant code, let's automatically upgrade
cpus_have_const_cap() to cpus_have_final_cap() when used in hyp context.
With this change, there's never a reason to access to cpu_hwcaps array
from hyp code, and we don't need to create an NVHE alias for this.
This should have no effect on non-hyp code.
Signed-off-by: Mark Rutland <mark.rutland at arm.com>
Cc: David Brazdil <dbrazdil at google.com>
Cc: Marc Zyngier <maz at kernel.org>
Cc: Will Deacon <will at kernel.org>
---
arch/arm64/include/asm/cpufeature.h | 26 ++++++++++++++++++++++++--
arch/arm64/include/asm/virt.h | 12 ------------
arch/arm64/kernel/image-vars.h | 1 -
3 files changed, 24 insertions(+), 15 deletions(-)
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 9f671aa0419b7..79d6a0371c78a 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -375,6 +375,23 @@ cpucap_multi_entry_cap_matches(const struct arm64_cpu_capabilities *entry,
return false;
}
+static __always_inline bool is_vhe_hyp_code(void)
+{
+ /* Only defined for code run in VHE hyp context */
+ return __is_defined(__KVM_VHE_HYPERVISOR__);
+}
+
+static __always_inline bool is_nvhe_hyp_code(void)
+{
+ /* Only defined for code run in NVHE hyp context */
+ return __is_defined(__KVM_NVHE_HYPERVISOR__);
+}
+
+static __always_inline bool is_hyp_code(void)
+{
+ return is_vhe_hyp_code() || is_nvhe_hyp_code();
+}
+
extern DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS);
extern struct static_key_false cpu_hwcap_keys[ARM64_NCAPS];
extern struct static_key_false arm64_const_caps_ready;
@@ -444,8 +461,11 @@ static __always_inline bool cpus_have_final_cap(int num)
}
/*
- * Test for a capability, possibly with a runtime check.
+ * Test for a capability, possibly with a runtime check for non-hyp code.
*
+ * For hyp code, this behaves the same as cpus_have_final_cap().
+ *
+ * For non-hyp code:
* Before capabilities are finalized, this behaves as cpus_have_cap().
* After capabilities are finalized, this is patched to avoid a runtime check.
*
@@ -453,7 +473,9 @@ static __always_inline bool cpus_have_final_cap(int num)
*/
static __always_inline bool cpus_have_const_cap(int num)
{
- if (system_capabilities_finalized())
+ if (is_hyp_code())
+ return cpus_have_final_cap(num);
+ else if (system_capabilities_finalized())
return __cpus_have_const_cap(num);
else
return cpus_have_cap(num);
diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
index 300be14ba77b2..6069be50baf9f 100644
--- a/arch/arm64/include/asm/virt.h
+++ b/arch/arm64/include/asm/virt.h
@@ -83,18 +83,6 @@ static inline bool is_kernel_in_hyp_mode(void)
return read_sysreg(CurrentEL) == CurrentEL_EL2;
}
-static __always_inline bool is_vhe_hyp_code(void)
-{
- /* Only defined for code run in VHE hyp context */
- return __is_defined(__KVM_VHE_HYPERVISOR__);
-}
-
-static __always_inline bool is_nvhe_hyp_code(void)
-{
- /* Only defined for code run in NVHE hyp context */
- return __is_defined(__KVM_NVHE_HYPERVISOR__);
-}
-
static __always_inline bool has_vhe(void)
{
/*
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index fbd4b6b1fde5d..ad8432251733e 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -87,7 +87,6 @@ KVM_NVHE_ALIAS(__icache_flags);
/* Kernel symbols needed for cpus_have_final/const_caps checks. */
KVM_NVHE_ALIAS(arm64_const_caps_ready);
KVM_NVHE_ALIAS(cpu_hwcap_keys);
-KVM_NVHE_ALIAS(cpu_hwcaps);
/* Static keys which are set if a vGIC trap should be handled in hyp. */
KVM_NVHE_ALIAS(vgic_v2_cpuif_trap);
--
2.11.0
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