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Date: Tue, 13 Feb 2018 09:05:40 +0800
From: Wanpeng Li <kernellwp@...il.com>
To: linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Radim Krčmář <rkrcmar@...hat.com>,
Eduardo Habkost <ehabkost@...hat.com>
Subject: [PATCH v4 1/3] KVM: Introduce dedicated vCPUs hint KVM_HINTS_DEDICATED
From: Wanpeng Li <wanpengli@...cent.com>
This patch introduces dedicated vCPUs(vCPU pinning, and there is
no vCPU over-commitment) hint KVM_HINTS_DEDICATED, guest checks
this feature bit to determine if they run on dedicated vCPUs,
allowing optimizations.
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Cc: Eduardo Habkost <ehabkost@...hat.com>
Signed-off-by: Wanpeng Li <wanpengli@...cent.com>
---
Documentation/virtual/kvm/cpuid.txt | 15 +++++++++++++--
arch/mips/include/asm/kvm_para.h | 5 +++++
arch/powerpc/include/asm/kvm_para.h | 5 +++++
arch/s390/include/asm/kvm_para.h | 5 +++++
arch/x86/include/asm/kvm_para.h | 6 ++++++
arch/x86/include/uapi/asm/kvm_para.h | 8 ++++++--
arch/x86/kernel/kvm.c | 5 +++++
include/asm-generic/kvm_para.h | 5 +++++
include/linux/kvm_para.h | 5 +++++
9 files changed, 55 insertions(+), 4 deletions(-)
diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt
index dcab6dc..1600768 100644
--- a/Documentation/virtual/kvm/cpuid.txt
+++ b/Documentation/virtual/kvm/cpuid.txt
@@ -23,8 +23,8 @@ This function queries the presence of KVM cpuid leafs.
function: define KVM_CPUID_FEATURES (0x40000001)
-returns : ebx, ecx, edx = 0
- eax = and OR'ed group of (1 << flag), where each flags is:
+returns : ebx, ecx
+ eax = an OR'ed group of (1 << flag), where each flags is:
flag || value || meaning
@@ -62,3 +62,14 @@ KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side
|| || per-cpu warps are expected in
|| || kvmclock.
------------------------------------------------------------------------------
+
+ edx = an OR'ed group of (1 << flag), where each flags is:
+
+
+flag || value || meaning
+==================================================================================
+KVM_HINTS_DEDICATED || 0 || guest checks this feature bit to
+ || || determine if there is vCPU pinning
+ || || and there is no vCPU over-commitment,
+ || || allowing optimizations
+----------------------------------------------------------------------------------
diff --git a/arch/mips/include/asm/kvm_para.h b/arch/mips/include/asm/kvm_para.h
index 60b1aa0..bd1f4ee 100644
--- a/arch/mips/include/asm/kvm_para.h
+++ b/arch/mips/include/asm/kvm_para.h
@@ -94,6 +94,11 @@ static inline unsigned int kvm_arch_para_features(void)
return 0;
}
+static inline unsigned int kvm_arch_hint_features(void)
+{
+ return 0;
+}
+
#ifdef CONFIG_MIPS_PARAVIRT
static inline bool kvm_para_available(void)
{
diff --git a/arch/powerpc/include/asm/kvm_para.h b/arch/powerpc/include/asm/kvm_para.h
index 336a91a..8e58c00 100644
--- a/arch/powerpc/include/asm/kvm_para.h
+++ b/arch/powerpc/include/asm/kvm_para.h
@@ -61,6 +61,11 @@ static inline unsigned int kvm_arch_para_features(void)
return r;
}
+static inline unsigned int kvm_arch_hint_features(void)
+{
+ return 0;
+}
+
static inline bool kvm_check_and_clear_guest_paused(void)
{
return false;
diff --git a/arch/s390/include/asm/kvm_para.h b/arch/s390/include/asm/kvm_para.h
index 74eeec9..b2c935c 100644
--- a/arch/s390/include/asm/kvm_para.h
+++ b/arch/s390/include/asm/kvm_para.h
@@ -193,6 +193,11 @@ static inline unsigned int kvm_arch_para_features(void)
return 0;
}
+static inline unsigned int kvm_arch_hint_features(void)
+{
+ return 0;
+}
+
static inline bool kvm_check_and_clear_guest_paused(void)
{
return false;
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 7b407dd..2c7d368 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -88,6 +88,7 @@ static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
#ifdef CONFIG_KVM_GUEST
bool kvm_para_available(void);
unsigned int kvm_arch_para_features(void);
+unsigned int kvm_arch_hint_features(void);
void kvm_async_pf_task_wait(u32 token, int interrupt_kernel);
void kvm_async_pf_task_wake(u32 token);
u32 kvm_read_and_reset_pf_reason(void);
@@ -115,6 +116,11 @@ static inline unsigned int kvm_arch_para_features(void)
return 0;
}
+static inline unsigned int kvm_arch_hint_features(void)
+{
+ return 0;
+}
+
static inline u32 kvm_read_and_reset_pf_reason(void)
{
return 0;
diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h
index 7a2ade4..e8f5dfb 100644
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -10,8 +10,10 @@
*/
#define KVM_CPUID_SIGNATURE 0x40000000
-/* This CPUID returns a feature bitmap in eax. Before enabling a particular
- * paravirtualization, the appropriate feature bit should be checked.
+/* This CPUID returns two feature bitmaps in eax, edx. Before enabling
+ * a particular paravirtualization, the appropriate feature bit should
+ * be checked in eax. The performance hint feature bit should be checked
+ * in edx.
*/
#define KVM_CPUID_FEATURES 0x40000001
#define KVM_FEATURE_CLOCKSOURCE 0
@@ -27,6 +29,8 @@
#define KVM_FEATURE_PV_UNHALT 7
#define KVM_FEATURE_PV_TLB_FLUSH 9
+#define KVM_HINTS_DEDICATED 0
+
/* The last 8 bits are used to indicate how to interpret the flags field
* in pvclock structure. If no bits are set, all flags are ignored.
*/
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 4e37d1a..77a0723 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -604,6 +604,11 @@ unsigned int kvm_arch_para_features(void)
return cpuid_eax(kvm_cpuid_base() | KVM_CPUID_FEATURES);
}
+unsigned int kvm_arch_hint_features(void)
+{
+ return cpuid_edx(kvm_cpuid_base() | KVM_CPUID_FEATURES);
+}
+
static uint32_t __init kvm_detect(void)
{
return kvm_cpuid_base();
diff --git a/include/asm-generic/kvm_para.h b/include/asm-generic/kvm_para.h
index 18c6abe..93e133d 100644
--- a/include/asm-generic/kvm_para.h
+++ b/include/asm-generic/kvm_para.h
@@ -19,6 +19,11 @@ static inline unsigned int kvm_arch_para_features(void)
return 0;
}
+static inline unsigned int kvm_arch_hint_features(void)
+{
+ return 0;
+}
+
static inline bool kvm_para_available(void)
{
return false;
diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
index 51f6ef2..30503b7 100644
--- a/include/linux/kvm_para.h
+++ b/include/linux/kvm_para.h
@@ -9,4 +9,9 @@ static inline bool kvm_para_has_feature(unsigned int feature)
{
return !!(kvm_arch_para_features() & (1UL << feature));
}
+
+static inline bool kvm_hint_has_feature(unsigned int feature)
+{
+ return !!(kvm_arch_hint_features() & (1UL << feature));
+}
#endif /* __LINUX_KVM_PARA_H */
--
2.7.4
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