[PATCH v5] kvm/fpu: Enable fully eager restore kvm FPU

[Xudong Hao <xudong.hao@intel.com>]

Romove fpu lazy restore logic, using eager restore totally.

v5 changes from v4:
- remove lazy fpu restore totally, fpu eager restore does not have performance
regression and simple the code.

v4 changes from v3:
- Wrap up some confused code with a clear function lazy_fpu_allowed()
- Update fpu while update cr4 too.

v3 changes from v2:
- Make fpu active explicitly while guest xsave is enabling and non-lazy xstate
bit exist.

v2 changes from v1:
- Expand KVM_XSTATE_LAZY to 64 bits before negating it.

Signed-off-by: Xudong Hao <xudong.hao@intel.com>
---
 arch/x86/kvm/vmx.c       | 9 ++-------
 arch/x86/kvm/x86.c       | 8 +-------
 include/linux/kvm_host.h | 1 -
 3 files changed, 3 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 6599e45..c1fd2e1 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1197,7 +1197,7 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu)
 	u32 eb;
 
 	eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) |
-	     (1u << NM_VECTOR) | (1u << DB_VECTOR);
+	     (1u << DB_VECTOR);
 	if ((vcpu->guest_debug &
 	     (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) ==
 	    (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP))
@@ -1206,8 +1206,6 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu)
 		eb = ~0;
 	if (enable_ept)
 		eb &= ~(1u << PF_VECTOR); /* bypass_guest_pf = 0 */
-	if (vcpu->fpu_active)
-		eb &= ~(1u << NM_VECTOR);
 
 	/* When we are running a nested L2 guest and L1 specified for it a
 	 * certain exception bitmap, we must trap the same exceptions and pass
@@ -3022,9 +3020,6 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
 	if (enable_ept)
 		ept_update_paging_mode_cr0(&hw_cr0, cr0, vcpu);
 
-	if (!vcpu->fpu_active)
-		hw_cr0 |= X86_CR0_TS | X86_CR0_MP;
-
 	vmcs_writel(CR0_READ_SHADOW, cr0);
 	vmcs_writel(GUEST_CR0, hw_cr0);
 	vcpu->arch.cr0 = cr0;
@@ -7119,7 +7114,7 @@ void load_vmcs12_host_state(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
 	 * but we also need to update cr0_guest_host_mask and exception_bitmap.
 	 */
 	update_exception_bitmap(vcpu);
-	vcpu->arch.cr0_guest_owned_bits = (vcpu->fpu_active ? X86_CR0_TS : 0);
+	vcpu->arch.cr0_guest_owned_bits = X86_CR0_TS;
 	vmcs_writel(CR0_GUEST_HOST_MASK, ~vcpu->arch.cr0_guest_owned_bits);
 
 	/*
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 49fa1f0..cd5aafe 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5275,10 +5275,6 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 			r = 0;
 			goto out;
 		}
-		if (kvm_check_request(KVM_REQ_DEACTIVATE_FPU, vcpu)) {
-			vcpu->fpu_active = 0;
-			kvm_x86_ops->fpu_deactivate(vcpu);
-		}
 		if (kvm_check_request(KVM_REQ_APF_HALT, vcpu)) {
 			/* Page is swapped out. Do synthetic halt */
 			vcpu->arch.apf.halted = true;
@@ -5320,8 +5316,7 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 	preempt_disable();
 
 	kvm_x86_ops->prepare_guest_switch(vcpu);
-	if (vcpu->fpu_active)
-		kvm_load_guest_fpu(vcpu);
+	kvm_load_guest_fpu(vcpu);
 	kvm_load_guest_xcr0(vcpu);
 
 	vcpu->mode = IN_GUEST_MODE;
@@ -6007,7 +6002,6 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
 	fpu_save_init(&vcpu->arch.guest_fpu);
 	__kernel_fpu_end();
 	++vcpu->stat.fpu_reload;
-	kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
 	trace_kvm_fpu(0);
 }
 
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 99a4762..0b33163 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -122,7 +122,6 @@ static inline bool is_error_page(struct page *page)
 #define KVM_REQ_MMU_SYNC           7
 #define KVM_REQ_CLOCK_UPDATE       8
 #define KVM_REQ_KICK               9
-#define KVM_REQ_DEACTIVATE_FPU    10
 #define KVM_REQ_EVENT             11
 #define KVM_REQ_APF_HALT          12
 #define KVM_REQ_STEAL_UPDATE      13
-- 
1.7.12.1