RE: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
-Original Message-
From: Avi Kivity [mailto:a...@redhat.com]
Sent: Monday, September 10, 2012 4:07 PM
To: Hao, Xudong
Cc: kvm@vger.kernel.org; Zhang, Xiantao; joerg.roe...@amd.com
Subject: Re: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
Avi, I'm not sure if I fully understand of you. Do you mean enter guest
with a
fpu_active=0 and then fpu does not restore?
Yes.
If so, I will add fpu_active=1 in the no-lazy case.
- kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+ if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE)
+ (vcpu-arch.xcr0 ~((u64)KVM_XSTATE_LAZY))) {
+ kvm_x86_ops-fpu_activate(vcpu);
+ vcpu-fpu_active=1;
+ }
+ else
+ kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
It doesn't help here.
1 guest boot
2 kvm_userspace_exit (deactivates fpu)
3 XSETBV exit that sets xcr0.new_bit
4 kvm_enter
There is no call to kvm_put_guest_fpu() between 3 and 4, you need
something in __kvm_set_xcr() to activate the fpu.
Yes, it's code path when enable xsave in guest, I'll add fpu activate there and
remain v2 patch in kvm_put_guest_fpu().
@@ -554,6 +554,8 @@ int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
xcr0 = xcr;
if (kvm_x86_ops-get_cpl(vcpu) != 0)
return 1;
+ if (xcr0 ~((u64)KVM_XSTATE_LAZY))
+ kvm_x86_ops-fpu_activate(vcpu);
if (!(xcr0 XSTATE_FP))
return 1;
if ((xcr0 XSTATE_YMM) !(xcr0 XSTATE_SSE))
Note you also need to consider writes to xcr0 and cr4 that happen in the
reverse order due to live migration.
I'm confused of this, doesn't setting cr4 firstly then xcr0?
Do you mean current live migration has a reverse order, or it must be a reverse
order with my eager restore patch?
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Re: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
On 09/11/2012 09:43 AM, Hao, Xudong wrote:
-Original Message-
From: Avi Kivity [mailto:a...@redhat.com]
Sent: Monday, September 10, 2012 4:07 PM
To: Hao, Xudong
Cc: kvm@vger.kernel.org; Zhang, Xiantao; joerg.roe...@amd.com
Subject: Re: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
Avi, I'm not sure if I fully understand of you. Do you mean enter guest
with a
fpu_active=0 and then fpu does not restore?
Yes.
If so, I will add fpu_active=1 in the no-lazy case.
- kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+ if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE)
+ (vcpu-arch.xcr0 ~((u64)KVM_XSTATE_LAZY))) {
+ kvm_x86_ops-fpu_activate(vcpu);
+ vcpu-fpu_active=1;
+ }
+ else
+ kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
It doesn't help here.
1 guest boot
2 kvm_userspace_exit (deactivates fpu)
3 XSETBV exit that sets xcr0.new_bit
4 kvm_enter
There is no call to kvm_put_guest_fpu() between 3 and 4, you need
something in __kvm_set_xcr() to activate the fpu.
Yes, it's code path when enable xsave in guest, I'll add fpu activate there
and remain v2 patch in kvm_put_guest_fpu().
@@ -554,6 +554,8 @@ int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64
xcr)
xcr0 = xcr;
if (kvm_x86_ops-get_cpl(vcpu) != 0)
return 1;
+ if (xcr0 ~((u64)KVM_XSTATE_LAZY))
+ kvm_x86_ops-fpu_activate(vcpu);
if (!(xcr0 XSTATE_FP))
return 1;
if ((xcr0 XSTATE_YMM) !(xcr0 XSTATE_SSE))
Note you also need to consider writes to xcr0 and cr4 that happen in the
reverse order due to live migration.
I'm confused of this, doesn't setting cr4 firstly then xcr0?
Do you mean current live migration has a reverse order, or it must be a
reverse order with my eager restore patch?
I mean I want the code to work regardless of whether KVM_SET_SREGS or
KVM_SET_XCRS is called first.
--
error compiling committee.c: too many arguments to function
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RE: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
-Original Message-
From: Avi Kivity [mailto:a...@redhat.com]
Sent: Tuesday, September 11, 2012 3:54 PM
To: Hao, Xudong
Cc: kvm@vger.kernel.org; Zhang, Xiantao; joerg.roe...@amd.com
Subject: Re: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
On 09/11/2012 09:43 AM, Hao, Xudong wrote:
-Original Message-
From: Avi Kivity [mailto:a...@redhat.com]
Sent: Monday, September 10, 2012 4:07 PM
To: Hao, Xudong
Cc: kvm@vger.kernel.org; Zhang, Xiantao; joerg.roe...@amd.com
Subject: Re: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
Avi, I'm not sure if I fully understand of you. Do you mean enter guest
with
a
fpu_active=0 and then fpu does not restore?
Yes.
If so, I will add fpu_active=1 in the no-lazy case.
- kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+ if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE)
+ (vcpu-arch.xcr0 ~((u64)KVM_XSTATE_LAZY))) {
+ kvm_x86_ops-fpu_activate(vcpu);
+ vcpu-fpu_active=1;
+ }
+ else
+ kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
It doesn't help here.
1 guest boot
2 kvm_userspace_exit (deactivates fpu)
3 XSETBV exit that sets xcr0.new_bit
4 kvm_enter
There is no call to kvm_put_guest_fpu() between 3 and 4, you need
something in __kvm_set_xcr() to activate the fpu.
Yes, it's code path when enable xsave in guest, I'll add fpu activate there
and
remain v2 patch in kvm_put_guest_fpu().
@@ -554,6 +554,8 @@ int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index,
u64 xcr)
xcr0 = xcr;
if (kvm_x86_ops-get_cpl(vcpu) != 0)
return 1;
+ if (xcr0 ~((u64)KVM_XSTATE_LAZY))
+ kvm_x86_ops-fpu_activate(vcpu);
if (!(xcr0 XSTATE_FP))
return 1;
if ((xcr0 XSTATE_YMM) !(xcr0 XSTATE_SSE))
Note you also need to consider writes to xcr0 and cr4 that happen in the
reverse order due to live migration.
I'm confused of this, doesn't setting cr4 firstly then xcr0?
Do you mean current live migration has a reverse order, or it must be a
reverse order with my eager restore patch?
I mean I want the code to work regardless of whether KVM_SET_SREGS or
KVM_SET_XCRS is called first.
Okay, I got it.
fpu_active(vcpu) in __kvm_set_xcr () read guest cr0, so KVM_SET_XCRS depends on
KVM_SET_SREGS in live migration case.
Here only set fpu_active=1 in __kvm_set_xcr(), and clear TS bit in set_cr0
should solve this issue.
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3028,6 +3028,8 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned
long cr0)
if (!vcpu-fpu_active)
hw_cr0 |= X86_CR0_TS | X86_CR0_MP;
+ else
+ hw_cr0 = ~(X86_CR0_TS | X86_CR0_MP);
vmcs_writel(CR0_READ_SHADOW, cr0);
vmcs_writel(GUEST_CR0, hw_cr0);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 20f2266..183cf60 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -560,6 +560,8 @@ int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
return 1;
if (xcr0 ~host_xcr0)
return 1;
+ if (xcr0 ~((u64)KVM_XSTATE_LAZY))
+ vcpu-fpu_active = 1;
vcpu-arch.xcr0 = xcr0;
vcpu-guest_xcr0_loaded = 0;
return 0;
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Re: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
On 09/10/2012 06:29 AM, Hao, Xudong wrote:
Doesn't help. We can have:
host: deactivate fpu for some reason
guest: set cr4.osxsave, xcr0.bit3
host: enter guest with deactivated fpu
guest: touch fpu
result: host fpu corrupted.
Avi, I'm not sure if I fully understand of you. Do you mean enter guest with
a fpu_active=0 and then fpu does not restore?
Yes.
If so, I will add fpu_active=1 in the no-lazy case.
- kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+ if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE)
+ (vcpu-arch.xcr0 ~((u64)KVM_XSTATE_LAZY))) {
+ kvm_x86_ops-fpu_activate(vcpu);
+ vcpu-fpu_active=1;
+ }
+ else
+ kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
It doesn't help here.
1 guest boot
2 kvm_userspace_exit (deactivates fpu)
3 XSETBV exit that sets xcr0.new_bit
4 kvm_enter
There is no call to kvm_put_guest_fpu() between 3 and 4, you need
something in __kvm_set_xcr() to activate the fpu.
kvm_put_guest_fpu() doesn't need to activate the fpu then, just to avoid
deactivating it.
Note you also need to consider writes to xcr0 and cr4 that happen in the
reverse order due to live migration.
--
error compiling committee.c: too many arguments to function
--
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the body of a message to majord...@vger.kernel.org
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RE: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
-Original Message-
From: kvm-ow...@vger.kernel.org [mailto:kvm-ow...@vger.kernel.org] On
Behalf Of Avi Kivity
Sent: Thursday, September 06, 2012 4:16 PM
To: Hao, Xudong
Cc: kvm@vger.kernel.org; Zhang, Xiantao; joerg.roe...@amd.com
Subject: Re: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
On 09/06/2012 05:13 AM, Hao, Xudong wrote:
-Original Message-
From: Avi Kivity [mailto:a...@redhat.com]
Sent: Wednesday, September 05, 2012 9:13 PM
To: Hao, Xudong
Cc: kvm@vger.kernel.org; Zhang, Xiantao; joerg.roe...@amd.com
Subject: Re: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
On 09/05/2012 04:26 AM, Xudong Hao wrote:
Enable KVM FPU fully eager restore, if there is other FPU state which
isn't
tracked by CR0.TS bit.
Changes from v1:
Expand KVM_XSTATE_LAZY to 64 bits before negating it.
Signed-off-by: Xudong Hao xudong@intel.com
---
arch/x86/include/asm/kvm.h |4
arch/x86/kvm/x86.c | 13 -
2 files changed, 16 insertions(+), 1 deletions(-)
diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
index 521bf25..4c27056 100644
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -8,6 +8,8 @@
#include linux/types.h
#include linux/ioctl.h
+#include asm/user.h
+#include asm/xsave.h
/* Select x86 specific features in linux/kvm.h */
#define __KVM_HAVE_PIT
@@ -30,6 +32,8 @@
/* Architectural interrupt line count. */
#define KVM_NR_INTERRUPTS 256
+#define KVM_XSTATE_LAZY (XSTATE_FP | XSTATE_SSE | XSTATE_YMM)
+
struct kvm_memory_alias {
__u32 slot; /* this has a different namespace than memory
slots */
__u32 flags;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 20f2266..a632042 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5969,7 +5969,18 @@ void kvm_put_guest_fpu(struct kvm_vcpu
*vcpu)
vcpu-guest_fpu_loaded = 0;
fpu_save_init(vcpu-arch.guest_fpu);
++vcpu-stat.fpu_reload;
-kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+/*
+ * Currently KVM trigger FPU restore by #NM (via CR0.TS),
+ * till now only XCR0.bit0, XCR0.bit1, XCR0.bit2 is tracked
+ * by TS bit, there might be other FPU state is not tracked
+ * by TS bit. Here it only make FPU deactivate request and do
+ * FPU lazy restore for these cases: 1)xsave isn't enabled
+ * in guest, 2)all guest FPU states can be tracked by TS bit.
+ * For others, doing fully FPU eager restore.
+ */
+if (!kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) ||
+!(vcpu-arch.xcr0 ~((u64)KVM_XSTATE_LAZY)))
+kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
trace_kvm_fpu(0);
}
I think something is missing. This patch prevents
KVM_REQ_DEACTIVATE_FPU, but the fpu may not be active when non-lazy
bits
are added to xcr0 (or cr4.osxsave is enabled). I think you need to
activate the fpu at that time as well.
Mmh, I thought fpu is active by default, but it's better to make fpu active
explicitly here.
If the following patch is fine, I'll make it another version.
It is, but a previous pass through kvm_put_guest_fpu() could have
deactivated it.
- kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+ if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE)
+ (vcpu-arch.xcr0 ~((u64)KVM_XSTATE_LAZY)))
+ kvm_x86_ops-fpu_activate(vcpu);
+ else
+ kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
Doesn't help. We can have:
host: deactivate fpu for some reason
guest: set cr4.osxsave, xcr0.bit3
host: enter guest with deactivated fpu
guest: touch fpu
result: host fpu corrupted.
Avi, I'm not sure if I fully understand of you. Do you mean enter guest with a
fpu_active=0 and then fpu does not restore? If so, I will add fpu_active=1 in
the no-lazy case.
- kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+ if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE)
+ (vcpu-arch.xcr0 ~((u64)KVM_XSTATE_LAZY))) {
+ kvm_x86_ops-fpu_activate(vcpu);
+ vcpu-fpu_active=1;
+ }
+ else
+ kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
--
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Re: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
On 09/06/2012 05:13 AM, Hao, Xudong wrote:
-Original Message-
From: Avi Kivity [mailto:a...@redhat.com]
Sent: Wednesday, September 05, 2012 9:13 PM
To: Hao, Xudong
Cc: kvm@vger.kernel.org; Zhang, Xiantao; joerg.roe...@amd.com
Subject: Re: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
On 09/05/2012 04:26 AM, Xudong Hao wrote:
Enable KVM FPU fully eager restore, if there is other FPU state which isn't
tracked by CR0.TS bit.
Changes from v1:
Expand KVM_XSTATE_LAZY to 64 bits before negating it.
Signed-off-by: Xudong Hao xudong@intel.com
---
arch/x86/include/asm/kvm.h |4
arch/x86/kvm/x86.c | 13 -
2 files changed, 16 insertions(+), 1 deletions(-)
diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
index 521bf25..4c27056 100644
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -8,6 +8,8 @@
#include linux/types.h
#include linux/ioctl.h
+#include asm/user.h
+#include asm/xsave.h
/* Select x86 specific features in linux/kvm.h */
#define __KVM_HAVE_PIT
@@ -30,6 +32,8 @@
/* Architectural interrupt line count. */
#define KVM_NR_INTERRUPTS 256
+#define KVM_XSTATE_LAZY (XSTATE_FP | XSTATE_SSE | XSTATE_YMM)
+
struct kvm_memory_alias {
__u32 slot; /* this has a different namespace than memory slots */
__u32 flags;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 20f2266..a632042 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5969,7 +5969,18 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
vcpu-guest_fpu_loaded = 0;
fpu_save_init(vcpu-arch.guest_fpu);
++vcpu-stat.fpu_reload;
- kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+ /*
+ * Currently KVM trigger FPU restore by #NM (via CR0.TS),
+ * till now only XCR0.bit0, XCR0.bit1, XCR0.bit2 is tracked
+ * by TS bit, there might be other FPU state is not tracked
+ * by TS bit. Here it only make FPU deactivate request and do
+ * FPU lazy restore for these cases: 1)xsave isn't enabled
+ * in guest, 2)all guest FPU states can be tracked by TS bit.
+ * For others, doing fully FPU eager restore.
+ */
+ if (!kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) ||
+ !(vcpu-arch.xcr0 ~((u64)KVM_XSTATE_LAZY)))
+ kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
trace_kvm_fpu(0);
}
I think something is missing. This patch prevents
KVM_REQ_DEACTIVATE_FPU, but the fpu may not be active when non-lazy bits
are added to xcr0 (or cr4.osxsave is enabled). I think you need to
activate the fpu at that time as well.
Mmh, I thought fpu is active by default, but it's better to make fpu active
explicitly here.
If the following patch is fine, I'll make it another version.
It is, but a previous pass through kvm_put_guest_fpu() could have
deactivated it.
- kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+ if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE)
+ (vcpu-arch.xcr0 ~((u64)KVM_XSTATE_LAZY)))
+ kvm_x86_ops-fpu_activate(vcpu);
+ else
+ kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
Doesn't help. We can have:
host: deactivate fpu for some reason
guest: set cr4.osxsave, xcr0.bit3
host: enter guest with deactivated fpu
guest: touch fpu
result: host fpu corrupted.
--
error compiling committee.c: too many arguments to function
--
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the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
On 09/05/2012 04:26 AM, Xudong Hao wrote:
Enable KVM FPU fully eager restore, if there is other FPU state which isn't
tracked by CR0.TS bit.
Changes from v1:
Expand KVM_XSTATE_LAZY to 64 bits before negating it.
Signed-off-by: Xudong Hao xudong@intel.com
---
arch/x86/include/asm/kvm.h |4
arch/x86/kvm/x86.c | 13 -
2 files changed, 16 insertions(+), 1 deletions(-)
diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
index 521bf25..4c27056 100644
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -8,6 +8,8 @@
#include linux/types.h
#include linux/ioctl.h
+#include asm/user.h
+#include asm/xsave.h
/* Select x86 specific features in linux/kvm.h */
#define __KVM_HAVE_PIT
@@ -30,6 +32,8 @@
/* Architectural interrupt line count. */
#define KVM_NR_INTERRUPTS 256
+#define KVM_XSTATE_LAZY (XSTATE_FP | XSTATE_SSE | XSTATE_YMM)
+
struct kvm_memory_alias {
__u32 slot; /* this has a different namespace than memory slots */
__u32 flags;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 20f2266..a632042 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5969,7 +5969,18 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
vcpu-guest_fpu_loaded = 0;
fpu_save_init(vcpu-arch.guest_fpu);
++vcpu-stat.fpu_reload;
- kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+ /*
+ * Currently KVM trigger FPU restore by #NM (via CR0.TS),
+ * till now only XCR0.bit0, XCR0.bit1, XCR0.bit2 is tracked
+ * by TS bit, there might be other FPU state is not tracked
+ * by TS bit. Here it only make FPU deactivate request and do
+ * FPU lazy restore for these cases: 1)xsave isn't enabled
+ * in guest, 2)all guest FPU states can be tracked by TS bit.
+ * For others, doing fully FPU eager restore.
+ */
+ if (!kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) ||
+ !(vcpu-arch.xcr0 ~((u64)KVM_XSTATE_LAZY)))
+ kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
trace_kvm_fpu(0);
}
I think something is missing. This patch prevents
KVM_REQ_DEACTIVATE_FPU, but the fpu may not be active when non-lazy bits
are added to xcr0 (or cr4.osxsave is enabled). I think you need to
activate the fpu at that time as well.
--
error compiling committee.c: too many arguments to function
--
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the body of a message to majord...@vger.kernel.org
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RE: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
-Original Message-
From: Avi Kivity [mailto:a...@redhat.com]
Sent: Wednesday, September 05, 2012 9:13 PM
To: Hao, Xudong
Cc: kvm@vger.kernel.org; Zhang, Xiantao; joerg.roe...@amd.com
Subject: Re: [PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
On 09/05/2012 04:26 AM, Xudong Hao wrote:
Enable KVM FPU fully eager restore, if there is other FPU state which isn't
tracked by CR0.TS bit.
Changes from v1:
Expand KVM_XSTATE_LAZY to 64 bits before negating it.
Signed-off-by: Xudong Hao xudong@intel.com
---
arch/x86/include/asm/kvm.h |4
arch/x86/kvm/x86.c | 13 -
2 files changed, 16 insertions(+), 1 deletions(-)
diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
index 521bf25..4c27056 100644
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -8,6 +8,8 @@
#include linux/types.h
#include linux/ioctl.h
+#include asm/user.h
+#include asm/xsave.h
/* Select x86 specific features in linux/kvm.h */
#define __KVM_HAVE_PIT
@@ -30,6 +32,8 @@
/* Architectural interrupt line count. */
#define KVM_NR_INTERRUPTS 256
+#define KVM_XSTATE_LAZY(XSTATE_FP | XSTATE_SSE | XSTATE_YMM)
+
struct kvm_memory_alias {
__u32 slot; /* this has a different namespace than memory slots */
__u32 flags;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 20f2266..a632042 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5969,7 +5969,18 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
vcpu-guest_fpu_loaded = 0;
fpu_save_init(vcpu-arch.guest_fpu);
++vcpu-stat.fpu_reload;
- kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+ /*
+* Currently KVM trigger FPU restore by #NM (via CR0.TS),
+* till now only XCR0.bit0, XCR0.bit1, XCR0.bit2 is tracked
+* by TS bit, there might be other FPU state is not tracked
+* by TS bit. Here it only make FPU deactivate request and do
+* FPU lazy restore for these cases: 1)xsave isn't enabled
+* in guest, 2)all guest FPU states can be tracked by TS bit.
+* For others, doing fully FPU eager restore.
+*/
+ if (!kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) ||
+ !(vcpu-arch.xcr0 ~((u64)KVM_XSTATE_LAZY)))
+ kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
trace_kvm_fpu(0);
}
I think something is missing. This patch prevents
KVM_REQ_DEACTIVATE_FPU, but the fpu may not be active when non-lazy bits
are added to xcr0 (or cr4.osxsave is enabled). I think you need to
activate the fpu at that time as well.
Mmh, I thought fpu is active by default, but it's better to make fpu active
explicitly here.
If the following patch is fine, I'll make it another version.
- kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+ if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE)
+ (vcpu-arch.xcr0 ~((u64)KVM_XSTATE_LAZY)))
+ kvm_x86_ops-fpu_activate(vcpu);
+ else
+ kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
Thanks,
-Xudong
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[PATCH v2] kvm/fpu: Enable fully eager restore kvm FPU
Enable KVM FPU fully eager restore, if there is other FPU state which isn't
tracked by CR0.TS bit.
Changes from v1:
Expand KVM_XSTATE_LAZY to 64 bits before negating it.
Signed-off-by: Xudong Hao xudong@intel.com
---
arch/x86/include/asm/kvm.h |4
arch/x86/kvm/x86.c | 13 -
2 files changed, 16 insertions(+), 1 deletions(-)
diff --git a/arch/x86/include/asm/kvm.h b/arch/x86/include/asm/kvm.h
index 521bf25..4c27056 100644
--- a/arch/x86/include/asm/kvm.h
+++ b/arch/x86/include/asm/kvm.h
@@ -8,6 +8,8 @@
#include linux/types.h
#include linux/ioctl.h
+#include asm/user.h
+#include asm/xsave.h
/* Select x86 specific features in linux/kvm.h */
#define __KVM_HAVE_PIT
@@ -30,6 +32,8 @@
/* Architectural interrupt line count. */
#define KVM_NR_INTERRUPTS 256
+#define KVM_XSTATE_LAZY(XSTATE_FP | XSTATE_SSE | XSTATE_YMM)
+
struct kvm_memory_alias {
__u32 slot; /* this has a different namespace than memory slots */
__u32 flags;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 20f2266..a632042 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5969,7 +5969,18 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
vcpu-guest_fpu_loaded = 0;
fpu_save_init(vcpu-arch.guest_fpu);
++vcpu-stat.fpu_reload;
- kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
+ /*
+* Currently KVM trigger FPU restore by #NM (via CR0.TS),
+* till now only XCR0.bit0, XCR0.bit1, XCR0.bit2 is tracked
+* by TS bit, there might be other FPU state is not tracked
+* by TS bit. Here it only make FPU deactivate request and do
+* FPU lazy restore for these cases: 1)xsave isn't enabled
+* in guest, 2)all guest FPU states can be tracked by TS bit.
+* For others, doing fully FPU eager restore.
+*/
+ if (!kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) ||
+ !(vcpu-arch.xcr0 ~((u64)KVM_XSTATE_LAZY)))
+ kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
trace_kvm_fpu(0);
}
--
1.5.5
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