Enable KVM FPU fully eager restore, if there is other FPU state which isn't
tracked by
CR0.TS bit.
Tested with these cases:
1) SpecCPU2000 workload( 1 VM, 2 VMs)
2) Program for floating point caculate
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 246617e..91aa1cd 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
@@ -29,6 +31,8 @@
/* 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 b6379e5..2e628e5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5966,7 +5966,18 @@ 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 & ~KVM_XSTATE_LAZY))
+ kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
trace_kvm_fpu(0);
}
--
1.5.5
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