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Date: Sun, 29 Apr 2007 18:50:17 +0300
From: Avi Kivity <avi@...ranet.com>
To: kvm-devel@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org,
Anthony Liguori <aliguori@...ibm.com>,
Avi Kivity <avi@...ranet.com>
Subject: [PATCH 2/7] KVM: VMX: Add lazy FPU support for VT
From: Anthony Liguori <aliguori@...ibm.com>
Only save/restore the FPU host state when the guest is actually using the
FPU.
Signed-off-by: Anthony Liguori <aliguori@...ibm.com>
Signed-off-by: Avi Kivity <avi@...ranet.com>
---
drivers/kvm/vmx.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++----
1 files changed, 52 insertions(+), 5 deletions(-)
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 0960811..1d2b41b 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -101,6 +101,13 @@ static inline int is_page_fault(u32 intr_info)
(INTR_TYPE_EXCEPTION | PF_VECTOR | INTR_INFO_VALID_MASK);
}
+static inline int is_no_device(u32 intr_info)
+{
+ return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VECTOR_MASK |
+ INTR_INFO_VALID_MASK)) ==
+ (INTR_TYPE_EXCEPTION | NM_VECTOR | INTR_INFO_VALID_MASK);
+}
+
static inline int is_external_interrupt(u32 intr_info)
{
return (intr_info & (INTR_INFO_INTR_TYPE_MASK | INTR_INFO_VALID_MASK))
@@ -216,6 +223,16 @@ static void vmcs_write64(unsigned long field, u64 value)
#endif
}
+static void vmcs_clear_bits(unsigned long field, u32 mask)
+{
+ vmcs_writel(field, vmcs_readl(field) & ~mask);
+}
+
+static void vmcs_set_bits(unsigned long field, u32 mask)
+{
+ vmcs_writel(field, vmcs_readl(field) | mask);
+}
+
/*
* Switches to specified vcpu, until a matching vcpu_put(), but assumes
* vcpu mutex is already taken.
@@ -833,6 +850,11 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
}
#endif
+ if (!(cr0 & CR0_TS_MASK)) {
+ vcpu->fpu_active = 1;
+ vmcs_clear_bits(EXCEPTION_BITMAP, CR0_TS_MASK);
+ }
+
vmcs_writel(CR0_READ_SHADOW, cr0);
vmcs_writel(GUEST_CR0,
(cr0 & ~KVM_GUEST_CR0_MASK) | KVM_VM_CR0_ALWAYS_ON);
@@ -842,6 +864,12 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
static void vmx_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
{
vmcs_writel(GUEST_CR3, cr3);
+
+ if (!(vcpu->cr0 & CR0_TS_MASK)) {
+ vcpu->fpu_active = 0;
+ vmcs_set_bits(GUEST_CR0, CR0_TS_MASK);
+ vmcs_set_bits(EXCEPTION_BITMAP, 1 << NM_VECTOR);
+ }
}
static void vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
@@ -1368,6 +1396,15 @@ static int handle_exception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
asm ("int $2");
return 1;
}
+
+ if (is_no_device(intr_info)) {
+ vcpu->fpu_active = 1;
+ vmcs_clear_bits(EXCEPTION_BITMAP, 1 << NM_VECTOR);
+ if (!(vcpu->cr0 & CR0_TS_MASK))
+ vmcs_clear_bits(GUEST_CR0, CR0_TS_MASK);
+ return 1;
+ }
+
error_code = 0;
rip = vmcs_readl(GUEST_RIP);
if (intr_info & INTR_INFO_DELIEVER_CODE_MASK)
@@ -1556,7 +1593,11 @@ static int handle_cr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
break;
case 2: /* clts */
vcpu_load_rsp_rip(vcpu);
- set_cr0(vcpu, vcpu->cr0 & ~CR0_TS_MASK);
+ vcpu->fpu_active = 1;
+ vmcs_clear_bits(EXCEPTION_BITMAP, 1 << NM_VECTOR);
+ vmcs_clear_bits(GUEST_CR0, CR0_TS_MASK);
+ vcpu->cr0 &= ~CR0_TS_MASK;
+ vmcs_writel(CR0_READ_SHADOW, vcpu->cr0);
skip_emulated_instruction(vcpu);
return 1;
case 1: /*mov from cr*/
@@ -1806,8 +1847,10 @@ again:
if (vcpu->guest_debug.enabled)
kvm_guest_debug_pre(vcpu);
- fx_save(vcpu->host_fx_image);
- fx_restore(vcpu->guest_fx_image);
+ if (vcpu->fpu_active) {
+ fx_save(vcpu->host_fx_image);
+ fx_restore(vcpu->guest_fx_image);
+ }
#ifdef CONFIG_X86_64
if (is_long_mode(vcpu)) {
@@ -1965,8 +2008,11 @@ again:
}
#endif
- fx_save(vcpu->guest_fx_image);
- fx_restore(vcpu->host_fx_image);
+ if (vcpu->fpu_active) {
+ fx_save(vcpu->guest_fx_image);
+ fx_restore(vcpu->host_fx_image);
+ }
+
vcpu->interrupt_window_open = (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & 3) == 0;
asm ("mov %0, %%ds; mov %0, %%es" : : "r"(__USER_DS));
@@ -2078,6 +2124,7 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
vmcs_clear(vmcs);
vcpu->vmcs = vmcs;
vcpu->launched = 0;
+ vcpu->fpu_active = 1;
return 0;
--
1.5.0.6
-
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