Re: kvm: provide synchronous registers in kvm_run
On 01/11/2012 11:20 AM, Christian Borntraeger wrote: Avi, Marcelo, here is the next version of the sync register patch series. A small hint for patch sets: $ git format-patch -n --cover-letter ... generates a / patch mail template that contains some summary about your set, like which files you modified. It can be very helpful to at first glance see obviously wrong things :). Alex -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: kvm: provide synchronous registers in kvm_run
On 01/11/2012 11:20 AM, Christian Borntraeger wrote: Avi, Marcelo, here is the next version of the sync register patch series. Whole set is: Acked-by: Alexander Graf ag...@suse.de Very cool interface addition! Alex -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
kvm: provide synchronous registers in kvm_run
Avi, Marcelo, here is the next version of the sync register patch series. -- To unsubscribe from this list: send the line unsubscribe kvm in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [patch 1/3] kvm: provide synchronous registers in kvm_run
On 22.12.2011, at 12:56, Christian Borntraeger wrote:
From: Christian Borntraeger borntrae...@de.ibm.com
On some cpus the overhead for virtualization instructions is in the same
range as a system call. Having to call multiple ioctls to get set registers
will make userspace handled exits more expensive than necessary.
Lets provide two sections in kvm_run to have a shared save area for
guest registers.
1. the first section is read-only, to handle registers that have side-effects
2. the second section is read/write, e.g. for general purpose registers.
Signed-off-by: Christian Borntraeger borntrae...@de.ibm.com
---
Documentation/virtual/kvm/api.txt | 16
arch/ia64/include/asm/kvm.h |7 +++
arch/powerpc/include/asm/kvm.h|7 +++
arch/s390/include/asm/kvm.h |6 ++
arch/x86/include/asm/kvm.h|7 +++
include/linux/kvm.h | 13 +
6 files changed, 56 insertions(+)
Index: b/Documentation/virtual/kvm/api.txt
===
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1652,7 +1652,23 @@ developer registration required to acces
/* Fix the size of the union. */
char padding[256];
};
+ /* Here are two fields that allow to access often used registers
+ * directly, to avoid the overhead of the ioctl system call */
+ union {
+ /* registers which can be only read */
+ struct sync_ro_regs sync_ro_regs;
+ char padding[1024];
+ };
+ union {
+ /* read/write guest registers */
+ struct sync_rw_regs sync_rw_regs;
+ char padding[1024];
+ };
Why have 2 different structs?
Unions shouldn't be anonymous. Please give the union a name :).
Alex
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Re: [PATCH 1/4] kvm: provide synchronous registers in kvm_run
On 05.01.2012, at 10:54, Christian Borntraeger wrote:
On some cpus the overhead for virtualization instructions is in the same
range as a system call. Having to call multiple ioctls to get set registers
will make certain userspace handled exits more expensive than necessary.
Lets provide two sections in kvm_run to have a shared save area for
guest registers.
1. the first section is read-only, to handle registers that have side-effects
2. the second section is read/write, e.g. for general purpose registers.
We also provide two 64bit flags fields (architecture specific), that will
specify which parts of these fields are valid. Each bit will define that
a group of registers (like general purpose) or a single register is valid.
In that way we can extend and shrink the interface. (The structure definition
itself can only grow of course).
Signed-off-by: Christian Borntraeger borntrae...@de.ibm.com
---
Documentation/virtual/kvm/api.txt | 28
arch/ia64/include/asm/kvm.h |7 +++
arch/powerpc/include/asm/kvm.h|7 +++
arch/s390/include/asm/kvm.h |6 ++
arch/x86/include/asm/kvm.h|7 +++
include/linux/kvm.h | 20
6 files changed, 75 insertions(+), 0 deletions(-)
diff --git a/Documentation/virtual/kvm/api.txt
b/Documentation/virtual/kvm/api.txt
index da1f8fd..a149e22 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1693,6 +1693,34 @@ developer registration required to access it).
/* Fix the size of the union. */
char padding[256];
};
+
+ /*
+ * Here are two fields that allow to access often used registers
+ * directly, to avoid the overhead of the ioctl system call. Each
+ * register can be extended or reduced by having flag bits specifying
+ * if a group of registers is valid.
+ */
+ __u64 kvm_valid_sync_ro_regs;
+ __u64 kvm_valid_sync_rw_regs;
+ union {
+ /* registers which can be only read */
+ struct kvm_sync_ro_regs sync_ro;
+ char padding[1024];
+ };
+ union {
+ /* read/write guest registers */
+ struct kvm_sync_rw_regs sync_rw;
+ char padding[1024];
+ };
Ah, new patch set. Same comment here. Please give the union a name. Also, I
still don't understand why we need 2 structs. All we need is a bitmap that says
this field is dirty and then kernel space can decide to ignore it.
Alex
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Re: [PATCH 1/4] kvm: provide synchronous registers in kvm_run
On 01/09/2012 03:01 PM, Alexander Graf wrote:
On 05.01.2012, at 10:54, Christian Borntraeger wrote:
On some cpus the overhead for virtualization instructions is in the same
range as a system call. Having to call multiple ioctls to get set registers
will make certain userspace handled exits more expensive than necessary.
Lets provide two sections in kvm_run to have a shared save area for
guest registers.
1. the first section is read-only, to handle registers that have
side-effects
2. the second section is read/write, e.g. for general purpose registers.
We also provide two 64bit flags fields (architecture specific), that will
specify which parts of these fields are valid. Each bit will define that
a group of registers (like general purpose) or a single register is valid.
In that way we can extend and shrink the interface. (The structure
definition
itself can only grow of course).
Signed-off-by: Christian Borntraeger borntrae...@de.ibm.com
---
Documentation/virtual/kvm/api.txt | 28
arch/ia64/include/asm/kvm.h |7 +++
arch/powerpc/include/asm/kvm.h|7 +++
arch/s390/include/asm/kvm.h |6 ++
arch/x86/include/asm/kvm.h|7 +++
include/linux/kvm.h | 20
6 files changed, 75 insertions(+), 0 deletions(-)
diff --git a/Documentation/virtual/kvm/api.txt
b/Documentation/virtual/kvm/api.txt
index da1f8fd..a149e22 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1693,6 +1693,34 @@ developer registration required to access it).
/* Fix the size of the union. */
char padding[256];
};
+
+ /*
+* Here are two fields that allow to access often used registers
+ * directly, to avoid the overhead of the ioctl system call. Each
+ * register can be extended or reduced by having flag bits
specifying
+ * if a group of registers is valid.
+ */
+ __u64 kvm_valid_sync_ro_regs;
+ __u64 kvm_valid_sync_rw_regs;
+ union {
+ /* registers which can be only read */
+ struct kvm_sync_ro_regs sync_ro;
+ char padding[1024];
+ };
+ union {
+ /* read/write guest registers */
+ struct kvm_sync_rw_regs sync_rw;
+ char padding[1024];
+ };
Ah, new patch set. Same comment here. Please give the union a name. Also, I
still don't understand why we need 2 structs.
Right.
All we need is a bitmap that says this field is dirty and then kernel space
can decide to ignore it.
Makes sense.
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error compiling committee.c: too many arguments to function
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[PATCH 1/4] kvm: provide synchronous registers in kvm_run
On some cpus the overhead for virtualization instructions is in the same
range as a system call. Having to call multiple ioctls to get set registers
will make certain userspace handled exits more expensive than necessary.
Lets provide two sections in kvm_run to have a shared save area for
guest registers.
1. the first section is read-only, to handle registers that have side-effects
2. the second section is read/write, e.g. for general purpose registers.
We also provide two 64bit flags fields (architecture specific), that will
specify which parts of these fields are valid. Each bit will define that
a group of registers (like general purpose) or a single register is valid.
In that way we can extend and shrink the interface. (The structure definition
itself can only grow of course).
Signed-off-by: Christian Borntraeger borntrae...@de.ibm.com
---
Documentation/virtual/kvm/api.txt | 28
arch/ia64/include/asm/kvm.h |7 +++
arch/powerpc/include/asm/kvm.h|7 +++
arch/s390/include/asm/kvm.h |6 ++
arch/x86/include/asm/kvm.h|7 +++
include/linux/kvm.h | 20
6 files changed, 75 insertions(+), 0 deletions(-)
diff --git a/Documentation/virtual/kvm/api.txt
b/Documentation/virtual/kvm/api.txt
index da1f8fd..a149e22 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1693,6 +1693,34 @@ developer registration required to access it).
/* Fix the size of the union. */
char padding[256];
};
+
+ /*
+* Here are two fields that allow to access often used registers
+ * directly, to avoid the overhead of the ioctl system call. Each
+ * register can be extended or reduced by having flag bits specifying
+ * if a group of registers is valid.
+ */
+ __u64 kvm_valid_sync_ro_regs;
+ __u64 kvm_valid_sync_rw_regs;
+ union {
+ /* registers which can be only read */
+ struct kvm_sync_ro_regs sync_ro;
+ char padding[1024];
+ };
+ union {
+ /* read/write guest registers */
+ struct kvm_sync_rw_regs sync_rw;
+ char padding[1024];
+ };
+
+If KVM_CAP_SYNC_REGS is defined, these fields allow userspace to access
+certain guest registers without having to call SET/GET_*REGS. Thus we can
+avoid some system call overhead if userspace has to handle the exit.
+Userspace can query the validity of the structure by checking
+kvm_valid_sync_r[wo]_regs for specific bits. These bits are architecture
+specific and usually define the validity of a groups of registers. (e.g.
+one bit for general purpose registers)
+
};
6. Capabilities that can be enabled
diff --git a/arch/ia64/include/asm/kvm.h b/arch/ia64/include/asm/kvm.h
index bc90c75..bae1f1e 100644
--- a/arch/ia64/include/asm/kvm.h
+++ b/arch/ia64/include/asm/kvm.h
@@ -261,4 +261,11 @@ struct kvm_debug_exit_arch {
struct kvm_guest_debug_arch {
};
+/* definition of registers in kvm_run */
+struct kvm_sync_ro_regs {
+};
+
+struct kvm_sync_rw_regs {
+};
+
#endif
diff --git a/arch/powerpc/include/asm/kvm.h b/arch/powerpc/include/asm/kvm.h
index f7727d9..14b766b 100644
--- a/arch/powerpc/include/asm/kvm.h
+++ b/arch/powerpc/include/asm/kvm.h
@@ -265,6 +265,13 @@ struct kvm_debug_exit_arch {
struct kvm_guest_debug_arch {
};
+/* definition of registers in kvm_run */
+struct kvm_sync_ro_regs {
+};
+
+struct kvm_sync_rw_regs {
+};
+
#define KVM_REG_MASK 0x001f
#define KVM_REG_EXT_MASK 0xffe0
#define KVM_REG_GPR0x
diff --git a/arch/s390/include/asm/kvm.h b/arch/s390/include/asm/kvm.h
index 82b32a1..dda27a0 100644
--- a/arch/s390/include/asm/kvm.h
+++ b/arch/s390/include/asm/kvm.h
@@ -41,4 +41,10 @@ struct kvm_debug_exit_arch {
struct kvm_guest_debug_arch {
};
+/* definition of registers in kvm_run */
+struct kvm_sync_ro_regs {
+};
+
+struct kvm_sync_rw_regs {
+};
#endif
diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
index 4d8dcbd..fb32847 100644
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -321,4 +321,11 @@ struct kvm_xcrs {
__u64 padding[16];
};
+/* definition of registers in kvm_run */
+struct kvm_sync_ro_regs {
+};
+
+struct kvm_sync_rw_regs {
+};
+
#endif /* _ASM_X86_KVM_H */
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 68e67e5..9398672 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -273,6 +273,25 @@ struct kvm_run {
/* Fix the size of the union. */
char padding[256];
};
+
+ /*
+* Here are two fields that allow to access often used registers
+* directly, to avoid the overhead of the ioctl system call. Each
+* register can be extended or reduced by having flag bits specifying
+* if a group of registers is valid.
+*/
+
[patch 1/3] kvm: provide synchronous registers in kvm_run
From: Christian Borntraeger borntrae...@de.ibm.com
On some cpus the overhead for virtualization instructions is in the same
range as a system call. Having to call multiple ioctls to get set registers
will make userspace handled exits more expensive than necessary.
Lets provide two sections in kvm_run to have a shared save area for
guest registers.
1. the first section is read-only, to handle registers that have side-effects
2. the second section is read/write, e.g. for general purpose registers.
Signed-off-by: Christian Borntraeger borntrae...@de.ibm.com
---
Documentation/virtual/kvm/api.txt | 16
arch/ia64/include/asm/kvm.h |7 +++
arch/powerpc/include/asm/kvm.h|7 +++
arch/s390/include/asm/kvm.h |6 ++
arch/x86/include/asm/kvm.h|7 +++
include/linux/kvm.h | 13 +
6 files changed, 56 insertions(+)
Index: b/Documentation/virtual/kvm/api.txt
===
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1652,7 +1652,23 @@ developer registration required to acces
/* Fix the size of the union. */
char padding[256];
};
+ /* Here are two fields that allow to access often used registers
+ * directly, to avoid the overhead of the ioctl system call */
+ union {
+ /* registers which can be only read */
+ struct sync_ro_regs sync_ro_regs;
+ char padding[1024];
+ };
+ union {
+ /* read/write guest registers */
+ struct sync_rw_regs sync_rw_regs;
+ char padding[1024];
+ };
};
+These fields allow userspace to access certain guest registers without
+having to call SET/GET_*REGS. Thus we can avoid some system call
+overhead if userspace has to handle the exit. (only available if
+KVM_CAP_SYNC_REGS is set). The ioctls will still work.
6. Capabilities that can be enabled
Index: b/arch/ia64/include/asm/kvm.h
===
--- a/arch/ia64/include/asm/kvm.h
+++ b/arch/ia64/include/asm/kvm.h
@@ -261,4 +261,11 @@ struct kvm_debug_exit_arch {
struct kvm_guest_debug_arch {
};
+/* definition of registers in kvm_run */
+struct sync_ro_regs {
+};
+
+struct sync_rw_regs {
+};
+
#endif
Index: b/arch/powerpc/include/asm/kvm.h
===
--- a/arch/powerpc/include/asm/kvm.h
+++ b/arch/powerpc/include/asm/kvm.h
@@ -265,6 +265,13 @@ struct kvm_debug_exit_arch {
struct kvm_guest_debug_arch {
};
+/* definition of registers in kvm_run */
+struct sync_ro_regs {
+};
+
+struct sync_rw_regs {
+};
+
#define KVM_REG_MASK 0x001f
#define KVM_REG_EXT_MASK 0xffe0
#define KVM_REG_GPR0x
Index: b/arch/s390/include/asm/kvm.h
===
--- a/arch/s390/include/asm/kvm.h
+++ b/arch/s390/include/asm/kvm.h
@@ -41,4 +41,10 @@ struct kvm_debug_exit_arch {
struct kvm_guest_debug_arch {
};
+/* definition of registers in kvm_run */
+struct sync_ro_regs {
+};
+
+struct sync_rw_regs {
+};
#endif
Index: b/arch/x86/include/asm/kvm.h
===
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -321,4 +321,11 @@ struct kvm_xcrs {
__u64 padding[16];
};
+/* definition of registers in kvm_run */
+struct sync_ro_regs {
+};
+
+struct sync_rw_regs {
+};
+
#endif /* _ASM_X86_KVM_H */
Index: b/include/linux/kvm.h
===
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -273,6 +273,18 @@ struct kvm_run {
/* Fix the size of the union. */
char padding[256];
};
+ /* Here are two fields that allow to access often used registers
+ * directly, to avoid the overhead of the ioctl system call */
+ union {
+ /* registers which can be only read */
+ struct sync_ro_regs sync_ro_regs;
+ char padding[1024];
+ };
+ union {
+ /* read/write guest registers */
+ struct sync_rw_regs sync_rw_regs;
+ char padding[1024];
+ };
};
/* for KVM_REGISTER_COALESCED_MMIO / KVM_UNREGISTER_COALESCED_MMIO */
@@ -557,6 +569,7 @@ struct kvm_ppc_pvinfo {
#define KVM_CAP_MAX_VCPUS 66 /* returns max vcpus per vm */
#define KVM_CAP_PPC_PAPR 68
#define KVM_CAP_S390_GMAP 71
+#define KVM_CAP_SYNC_REGS 72
#ifdef KVM_CAP_IRQ_ROUTING
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Re: [patch 1/3] kvm: provide synchronous registers in kvm_run
On 12/22/2011 01:56 PM, Christian Borntraeger wrote:
From: Christian Borntraeger borntrae...@de.ibm.com
On some cpus the overhead for virtualization instructions is in the same
range as a system call. Having to call multiple ioctls to get set registers
will make userspace handled exits more expensive than necessary.
Lets provide two sections in kvm_run to have a shared save area for
guest registers.
1. the first section is read-only, to handle registers that have side-effects
2. the second section is read/write, e.g. for general purpose registers.
An alternative is to have a single section, with a bitmask set by
userspace to indicate which registers have not been changed (a la svm's
CleanBits). Is this worthwhile for s390?
};
+ /* Here are two fields that allow to access often used registers
+ * directly, to avoid the overhead of the ioctl system call */
+ union {
+ /* registers which can be only read */
+ struct sync_ro_regs sync_ro_regs;
kvm_
+ char padding[1024];
+ };
+ union {
+ /* read/write guest registers */
+ struct sync_rw_regs sync_rw_regs;
kvm_
+ char padding[1024];
+ };
};
blank line
+These fields allow userspace to access certain guest registers without
+having to call SET/GET_*REGS. Thus we can avoid some system call
+overhead if userspace has to handle the exit. (only available if
+KVM_CAP_SYNC_REGS is set). The ioctls will still work.
--
error compiling committee.c: too many arguments to function
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