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Date: Mon, 26 May 2014 10:01:21 -0700
From: "Fenghua Yu" <fenghua.yu@...el.com>
To: "H. Peter Anvin" <hpa@...ux.intel.com>,
"Ingo Molnar" <mingo@...e.hu>,
"Thomas Gleixner" <tglx@...utronix.de>,
"Asit K Mallick" <asit.k.mallick@...el.com>
Cc: "linux-kernel" <linux-kernel@...r.kernel.org>,
"x86" <x86@...nel.org>, "Fenghua Yu" <fenghua.yu@...el.com>
Subject: [PATCH 14/15] x86/xsaves: Enable xsaves/xrstors
From: Fenghua Yu <fenghua.yu@...el.com>
If xsaves/xrstors is enabled, compacted format of xsave area will be used
and less memory may be used for context switching per process. Modified
optimization implemented in xsaves/xrstors improves performance of saving
xstate as well.
Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
---
arch/x86/kernel/xsave.c | 38 ++++++++++++++++++++++++++++++++------
1 file changed, 32 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
index 8fa7c7d..2e9a77d 100644
--- a/arch/x86/kernel/xsave.c
+++ b/arch/x86/kernel/xsave.c
@@ -8,6 +8,7 @@
#include <linux/bootmem.h>
#include <linux/compat.h>
+#include <linux/cpu.h>
#include <asm/i387.h>
#include <asm/fpu-internal.h>
#include <asm/sigframe.h>
@@ -24,7 +25,9 @@ u64 pcntxt_mask;
struct xsave_struct *init_xstate_buf;
static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32;
-static unsigned int *xstate_offsets, *xstate_sizes, xstate_features;
+static unsigned int *xstate_offsets, *xstate_sizes;
+static unsigned int *xstate_comp_offsets, *xstate_comp_sizes;
+static unsigned int xstate_features;
/*
* If a processor implementation discern that a processor state component is
@@ -283,7 +286,7 @@ sanitize_restored_xstate(struct task_struct *tsk,
if (use_xsave()) {
/* These bits must be zero. */
- xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0;
+ memset(xsave_hdr->reserved, 0, 48);
/*
* Init the state that is not present in the memory
@@ -526,6 +529,30 @@ static int __init eager_fpu_setup(char *s)
}
__setup("eagerfpu=", eager_fpu_setup);
+
+/*
+ * Calculate total size of enabled xstates in XCR0/pcntxt_mask.
+ */
+static void __init init_xstate_size(void)
+{
+ unsigned int eax, ebx, ecx, edx;
+ int i;
+
+ if (!cpu_has_xsaves) {
+ cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
+ xstate_size = ebx;
+ return;
+ }
+
+ xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE;
+ for (i = 2; i < 64; i++) {
+ if (test_bit(i, (unsigned long *)&pcntxt_mask)) {
+ cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx);
+ xstate_size += eax;
+ }
+ }
+}
+
/*
* Enable and initialize the xsave feature.
*/
@@ -557,8 +584,7 @@ static void __init xstate_enable_boot_cpu(void)
/*
* Recompute the context size for enabled features
*/
- cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
- xstate_size = ebx;
+ init_xstate_size();
update_regset_xstate_info(xstate_size, pcntxt_mask);
prepare_fx_sw_frame();
@@ -578,8 +604,8 @@ static void __init xstate_enable_boot_cpu(void)
}
}
- pr_info("enabled xstate_bv 0x%llx, cntxt size 0x%x\n",
- pcntxt_mask, xstate_size);
+ pr_info("enabled xstate_bv 0x%llx, cntxt size 0x%x using %s\n",
+ pcntxt_mask, xstate_size, cpu_has_xsaves ? "xsaves" : "xsave");
}
/*
--
1.8.1.2
--
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