linux-kernel - [PATCH v2 14/17] arm64: Detect async PF para-virtualization feature

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210209050403.103143-15-gshan@redhat.com>
Date:   Tue,  9 Feb 2021 13:04:00 +0800
From:   Gavin Shan <gshan@...hat.com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     linux-kernel@...r.kernel.org, pbonzini@...hat.com, maz@...nel.org,
        james.morse@....com, Jonathan.Cameron@...wei.com,
        mark.rutland@....com, will@...nel.org, shan.gavin@...il.com
Subject: [PATCH v2 14/17] arm64: Detect async PF para-virtualization feature

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 <gshan@...hat.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 f39568b28ec1..792ae09aa690 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1078,6 +1078,17 @@ 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