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From: tip-bot for Andy Lutomirski <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: luto@kernel.org, bp@alien8.de, fenghua.yu@intel.com,
	oleg@redhat.com, peterz@infradead.org,
	dave.hansen@linux.intel.com, quentin.casasnovas@oracle.com,
	dvlasenk@redhat.com, kvm@vger.kernel.org, pbonzini@redhat.com,
	torvalds@linux-foundation.org, brgerst@gmail.com,
	mingo@kernel.org, linux-kernel@vger.kernel.org,
	rusty@rustcorp.com.au, jpoimboe@redhat.com, tglx@linutronix.de,
	riel@redhat.com, hpa@zytor.com
Subject: [tip:x86/fpu] x86/fpu, kvm: Remove host CR0.TS manipulation
Date: Tue, 1 Nov 2016 00:15:19 -0700	[thread overview]
Message-ID: <tip-04ac88abaf758bd76edcc3be5549003a017e7963@git.kernel.org> (raw)
In-Reply-To: <b212064922537c05d0c81d931fc4dbe769127ce7.1477951965.git.luto@kernel.org>

Commit-ID:  04ac88abaf758bd76edcc3be5549003a017e7963
Gitweb:     http://git.kernel.org/tip/04ac88abaf758bd76edcc3be5549003a017e7963
Author:     Andy Lutomirski <luto@kernel.org>
AuthorDate: Mon, 31 Oct 2016 15:18:45 -0700
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Tue, 1 Nov 2016 07:47:54 +0100

x86/fpu, kvm: Remove host CR0.TS manipulation

Now that x86 always uses eager FPU switching on the host, there's no
need for KVM to manipulate the host's CR0.TS.

This should be both simpler and faster.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm list <kvm@vger.kernel.org>
Link: http://lkml.kernel.org/r/b212064922537c05d0c81d931fc4dbe769127ce7.1477951965.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kvm/vmx.c | 12 ++++--------
 arch/x86/kvm/x86.c |  5 -----
 2 files changed, 4 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index cf1b16d..531c446 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2144,12 +2144,6 @@ static void __vmx_load_host_state(struct vcpu_vmx *vmx)
 #endif
 	if (vmx->host_state.msr_host_bndcfgs)
 		wrmsrl(MSR_IA32_BNDCFGS, vmx->host_state.msr_host_bndcfgs);
-	/*
-	 * If the FPU is not active (through the host task or
-	 * the guest vcpu), then restore the cr0.TS bit.
-	 */
-	if (!fpregs_active() && !vmx->vcpu.guest_fpu_loaded)
-		stts();
 	load_gdt(this_cpu_ptr(&host_gdt));
 }
 
@@ -4871,9 +4865,11 @@ static void vmx_set_constant_host_state(struct vcpu_vmx *vmx)
 	u32 low32, high32;
 	unsigned long tmpl;
 	struct desc_ptr dt;
-	unsigned long cr4;
+	unsigned long cr0, cr4;
 
-	vmcs_writel(HOST_CR0, read_cr0() & ~X86_CR0_TS);  /* 22.2.3 */
+	cr0 = read_cr0();
+	WARN_ON(cr0 & X86_CR0_TS);
+	vmcs_writel(HOST_CR0, cr0);  /* 22.2.3 */
 	vmcs_writel(HOST_CR3, read_cr3());  /* 22.2.3  FIXME: shadow tables */
 
 	/* Save the most likely value for this task's CR4 in the VMCS. */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7f9fa2d..cfe6a75b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5060,11 +5060,6 @@ static void emulator_get_fpu(struct x86_emulate_ctxt *ctxt)
 {
 	preempt_disable();
 	kvm_load_guest_fpu(emul_to_vcpu(ctxt));
-	/*
-	 * CR0.TS may reference the host fpu state, not the guest fpu state,
-	 * so it may be clear at this point.
-	 */
-	clts();
 }
 
 static void emulator_put_fpu(struct x86_emulate_ctxt *ctxt)

  reply	other threads:[~2016-11-01  7:17 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-31 22:18 [PATCH 0/8] x86/fpu: Remove CR0.TS support Andy Lutomirski
2016-10-31 22:18 ` [PATCH 1/8] fpu/init: Get rid of two redundant clts() calls Andy Lutomirski
2016-11-01  7:13   ` [tip:x86/fpu] x86/fpu: " tip-bot for Andy Lutomirski
2016-10-31 22:18 ` [PATCH 2/8] fpu/bugs: Stop saving and restoring CR0.TS in fpu__init_check_bugs() Andy Lutomirski
2016-11-01  7:14   ` [tip:x86/fpu] x86/fpu: " tip-bot for Andy Lutomirski
2016-10-31 22:18 ` [PATCH 3/8] x86/fpu: Remove irq_ts_save() and irq_ts_restore() Andy Lutomirski
2016-11-01  7:14   ` [tip:x86/fpu] " tip-bot for Andy Lutomirski
2016-10-31 22:18 ` [PATCH 4/8] x86/kvm: Remove host CR0.TS manipulation Andy Lutomirski
2016-11-01  7:15   ` tip-bot for Andy Lutomirski [this message]
2016-10-31 22:18 ` [PATCH 5/8] lguest: Remove CR0.TS support Andy Lutomirski
2016-11-01  7:15   ` [tip:x86/fpu] x86/fpu, " tip-bot for Andy Lutomirski
2016-10-31 22:18 ` [PATCH 6/8] x86/fpu: #NM without FPU emulation is an error Andy Lutomirski
2016-11-01  7:16   ` [tip:x86/fpu] x86/fpu: Handle #NM without FPU emulation as " tip-bot for Andy Lutomirski
2016-10-31 22:18 ` [PATCH 7/8] x86/fpu: Remove stts() Andy Lutomirski
2016-11-01  7:16   ` [tip:x86/fpu] " tip-bot for Andy Lutomirski
2016-10-31 22:18 ` [PATCH 8/8] x86/fpu: Remove clts() Andy Lutomirski
2016-11-01  7:17   ` [tip:x86/fpu] " tip-bot for Andy Lutomirski
2016-10-31 22:41 ` [PATCH 0/8] x86/fpu: Remove CR0.TS support Paul Bolle
2016-10-31 23:04   ` Borislav Petkov
2016-10-31 23:10     ` Paul Bolle
2016-10-31 23:48       ` Borislav Petkov
2016-11-01  7:51         ` Paul Bolle
2016-11-01  8:50           ` Borislav Petkov

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