From: riel@redhat.com
To: linux-kernel@vger.kernel.org
Cc: x86@kernel.org, tglx@linutronix.de, pbonzini@redhat.com,
mingo@redhat.com, luto@kernel.org, hpa@zytor.com,
dave.hansen@linux.intel.com, bp@suse.de
Subject: [PATCH RFC 3/5] x86,fpu: add kernel fpu argument to __kernel_fpu_begin
Date: Sat, 1 Oct 2016 16:31:33 -0400 [thread overview]
Message-ID: <1475353895-22175-4-git-send-email-riel@redhat.com> (raw)
In-Reply-To: <1475353895-22175-1-git-send-email-riel@redhat.com>
From: Rik van Riel <riel@redhat.com>
Most kernel FPU contexts are transient, but a KVM VCPU context
persists. Add a kernel FPU argument to __kernel_fpu_begin, so
we can know whether or not the KVM VCPU context got clobbered
by another kernel FPU context.
Signed-off-by: Rik van Riel <riel@redhat.com>
---
arch/x86/include/asm/efi.h | 2 +-
arch/x86/include/asm/fpu/api.h | 2 +-
arch/x86/kernel/fpu/core.c | 6 +++---
arch/x86/kvm/x86.c | 8 ++++++--
4 files changed, 11 insertions(+), 7 deletions(-)
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index d0bb76d81402..603d2cdd6b82 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -71,7 +71,7 @@ struct efi_scratch {
({ \
efi_sync_low_kernel_mappings(); \
preempt_disable(); \
- __kernel_fpu_begin(); \
+ __kernel_fpu_begin(NULL); \
\
if (efi_scratch.use_pgd) { \
efi_scratch.prev_cr3 = read_cr3(); \
diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
index edd7dc7ae4f7..f6704edf9904 100644
--- a/arch/x86/include/asm/fpu/api.h
+++ b/arch/x86/include/asm/fpu/api.h
@@ -20,7 +20,7 @@
* All other cases use kernel_fpu_begin/end() which disable preemption
* during kernel FPU usage.
*/
-extern void __kernel_fpu_begin(void);
+extern void __kernel_fpu_begin(struct fpu *fpu);
extern void __kernel_fpu_end(void);
extern void kernel_fpu_begin(void);
extern void kernel_fpu_end(void);
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index c4350f188be1..537eb65b6ae6 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -110,7 +110,7 @@ bool irq_fpu_usable(void)
}
EXPORT_SYMBOL(irq_fpu_usable);
-void __kernel_fpu_begin(void)
+void __kernel_fpu_begin(struct fpu *kernelfpu)
{
struct fpu *fpu = ¤t->thread.fpu;
@@ -118,7 +118,7 @@ void __kernel_fpu_begin(void)
kernel_fpu_disable();
- this_cpu_write(fpu_fpregs_owner_ctx, NULL);
+ this_cpu_write(fpu_fpregs_owner_ctx, kernelfpu);
if (fpu->fpregs_active) {
/*
@@ -150,7 +150,7 @@ EXPORT_SYMBOL(__kernel_fpu_end);
void kernel_fpu_begin(void)
{
preempt_disable();
- __kernel_fpu_begin();
+ __kernel_fpu_begin(NULL);
}
EXPORT_SYMBOL_GPL(kernel_fpu_begin);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 699f8726539a..55c82d066d3a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7332,6 +7332,8 @@ static void fx_init(struct kvm_vcpu *vcpu)
void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
{
+ struct fpu *fpu;
+
if (vcpu->guest_fpu_loaded)
return;
@@ -7340,9 +7342,11 @@ void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
* and assume host would use all available bits.
* Guest xcr0 would be loaded later.
*/
+ fpu = &vcpu->arch.guest_fpu;
+
vcpu->guest_fpu_loaded = 1;
- __kernel_fpu_begin();
- __copy_kernel_to_fpregs(&vcpu->arch.guest_fpu.state);
+ __kernel_fpu_begin(fpu);
+ __copy_kernel_to_fpregs(&fpu->state);
trace_kvm_fpu(1);
}
--
2.7.4
next prev parent reply other threads:[~2016-10-01 20:50 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-01 20:31 [PATCH RFC 0/5] x86,fpu: make FPU context switching much lazier riel
2016-10-01 20:31 ` [PATCH RFC 1/5] x86,fpu: split prev/next task fpu state handling riel
2016-10-01 23:26 ` Andy Lutomirski
2016-10-02 0:02 ` Rik van Riel
2016-10-01 20:31 ` [PATCH RFC 2/5] x86,fpu: delay FPU register loading until switch to userspace riel
2016-10-01 23:44 ` Andy Lutomirski
2016-10-02 0:08 ` Rik van Riel
2016-10-03 20:54 ` Andy Lutomirski
2016-10-03 21:21 ` Rik van Riel
2016-10-03 21:36 ` Andy Lutomirski
2016-10-04 1:29 ` Rik van Riel
2016-10-04 2:09 ` Andy Lutomirski
2016-10-04 2:47 ` Rik van Riel
2016-10-04 3:02 ` Andy Lutomirski
2016-10-04 6:35 ` Ingo Molnar
2016-10-04 12:48 ` Rik van Riel
2016-10-04 2:11 ` Rik van Riel
2016-10-04 3:02 ` Andy Lutomirski
2016-10-02 0:42 ` Rik van Riel
2016-10-03 16:23 ` Dave Hansen
2016-10-01 20:31 ` riel [this message]
2016-10-01 20:31 ` [PATCH RFC 4/5] x86,fpu: lazily skip FPU restore when still loaded riel
2016-10-03 20:04 ` Dave Hansen
2016-10-03 20:22 ` Rik van Riel
2016-10-03 20:49 ` Dave Hansen
2016-10-03 21:02 ` Rik van Riel
2016-10-01 20:31 ` [PATCH RFC 5/5] x86,fpu: kinda sorta fix up signal path riel
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