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 <gs...@redhat.com> --- 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 7f2a80091337..c03499c1acd6 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1104,6 +1104,17 @@ 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 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm