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Message-Id: <76d1f1eacb5caead98197d1eb50ac6110ab20c6a.1477951965.git.luto@kernel.org>
Date: Mon, 31 Oct 2016 15:18:43 -0700
From: Andy Lutomirski <luto@...nel.org>
To: x86@...nel.org
Cc: Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
Rusty Russell <rusty@...tcorp.com.au>,
Paolo Bonzini <pbonzini@...hat.com>,
Rik van Riel <riel@...hat.com>,
kvm list <kvm@...r.kernel.org>,
Andy Lutomirski <luto@...nel.org>
Subject: [PATCH 2/8] fpu/bugs: Stop saving and restoring CR0.TS in fpu__init_check_bugs()
fpu__init_check_bugs() runs long after the early FPU init, so CR0.TS
will be clear by the time it runs. The save-and-restore dance would
have been unnecessary anyway, though, as kernel_fpu_begin() would
have been good enough.
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
arch/x86/kernel/fpu/bugs.c | 7 -------
1 file changed, 7 deletions(-)
diff --git a/arch/x86/kernel/fpu/bugs.c b/arch/x86/kernel/fpu/bugs.c
index aad34aafc0e0..d913047f832c 100644
--- a/arch/x86/kernel/fpu/bugs.c
+++ b/arch/x86/kernel/fpu/bugs.c
@@ -23,17 +23,12 @@ static double __initdata y = 3145727.0;
*/
void __init fpu__init_check_bugs(void)
{
- u32 cr0_saved;
s32 fdiv_bug;
/* kernel_fpu_begin/end() relies on patched alternative instructions. */
if (!boot_cpu_has(X86_FEATURE_FPU))
return;
- /* We might have CR0::TS set already, clear it: */
- cr0_saved = read_cr0();
- write_cr0(cr0_saved & ~X86_CR0_TS);
-
kernel_fpu_begin();
/*
@@ -56,8 +51,6 @@ void __init fpu__init_check_bugs(void)
kernel_fpu_end();
- write_cr0(cr0_saved);
-
if (fdiv_bug) {
set_cpu_bug(&boot_cpu_data, X86_BUG_FDIV);
pr_warn("Hmm, FPU with FDIV bug\n");
--
2.7.4
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