[PATCH v4 12/15] arm64: Detect async PF para-virtualization feature
From: Gavin Shan <hidden>
Date: 2021-08-15 01:03:12
Also in:
kvmarm, lkml
Subsystem:
arm64 port (aarch64 architecture), kernel virtual machine for arm64 (kvm/arm64), the rest · Maintainers:
Catalin Marinas, Will Deacon, Marc Zyngier, Oliver Upton, Linus Torvalds
This implements kvm_para_available() to check if para-virtualization features are available or not. Besides, kvm_para_has_feature() is enhanced to detect the asynchronous page fault para-virtualization feature. These two functions are going to be used by guest kernel to enable the asynchronous page fault. This also adds kernel option (CONFIG_KVM_GUEST), which is the umbrella for the optimizations related to KVM para-virtualization. Signed-off-by: Gavin Shan <redacted> --- arch/arm64/Kconfig | 11 +++++++++++ arch/arm64/include/asm/kvm_para.h | 12 +++++++++++- arch/arm64/include/uapi/asm/kvm_para.h | 2 ++ 3 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index fdcd54d39c1e..6dceae6ed7d3 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig@@ -1081,6 +1081,17 @@ config PARAVIRT_TIME_ACCOUNTING If in doubt, say N here. +config KVM_GUEST + bool "KVM Guest Support" + depends on PARAVIRT + default y + help + This option enables various optimizations for running under the KVM + hypervisor. Overhead for the kernel when not running inside KVM should + be minimal. + + In case of doubt, say Y + config KEXEC depends on PM_SLEEP_SMP select KEXEC_CORE
diff --git a/arch/arm64/include/asm/kvm_para.h b/arch/arm64/include/asm/kvm_para.h
index 0ea481dd1c7a..8f39c60a6619 100644
--- a/arch/arm64/include/asm/kvm_para.h
+++ b/arch/arm64/include/asm/kvm_para.h@@ -3,6 +3,8 @@ #define _ASM_ARM_KVM_PARA_H #include <uapi/asm/kvm_para.h> +#include <linux/of.h> +#include <asm/hypervisor.h> static inline bool kvm_check_and_clear_guest_paused(void) {
@@ -11,7 +13,12 @@ static inline bool kvm_check_and_clear_guest_paused(void) static inline unsigned int kvm_arch_para_features(void) { - return 0; + unsigned int features = 0; + + if (kvm_arm_hyp_service_available(ARM_SMCCC_KVM_FUNC_ASYNC_PF)) + features |= (1 << KVM_FEATURE_ASYNC_PF); + + return features; } static inline unsigned int kvm_arch_para_hints(void)
@@ -21,6 +28,9 @@ static inline unsigned int kvm_arch_para_hints(void) static inline bool kvm_para_available(void) { + if (IS_ENABLED(CONFIG_KVM_GUEST)) + return true; + return false; }
diff --git a/arch/arm64/include/uapi/asm/kvm_para.h b/arch/arm64/include/uapi/asm/kvm_para.h
index 162325e2638f..70bbc7d1ec75 100644
--- a/arch/arm64/include/uapi/asm/kvm_para.h
+++ b/arch/arm64/include/uapi/asm/kvm_para.h@@ -4,6 +4,8 @@ #include <linux/types.h> +#define KVM_FEATURE_ASYNC_PF 0 + /* Async PF */ #define KVM_ASYNC_PF_ENABLED (1 << 0) #define KVM_ASYNC_PF_SEND_ALWAYS (1 << 1)
--
2.23.0