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/*
* xsave/xrstor support.
*
* Author: Suresh Siddha <suresh.b.siddha@intel.com>
*/
#include <linux/bootmem.h>
#include <linux/compat.h>
#include <asm/i387.h>
/*
* Supported feature mask by the CPU and the kernel.
*/
unsigned int pcntxt_hmask, pcntxt_lmask;
/*
* Represents init state for the supported extended state.
*/
struct xsave_struct *init_xstate_buf;
/*
* Enable the extended processor state save/restore feature
*/
void __cpuinit xsave_init(void)
{
if (!cpu_has_xsave)
return;
set_in_cr4(X86_CR4_OSXSAVE);
/*
* Enable all the features that the HW is capable of
* and the Linux kernel is aware of.
*
* xsetbv();
*/
asm volatile(".byte 0x0f,0x01,0xd1" : : "c" (0),
"a" (pcntxt_lmask), "d" (pcntxt_hmask));
}
/*
* setup the xstate image representing the init state
*/
void setup_xstate_init(void)
{
init_xstate_buf = alloc_bootmem(xstate_size);
init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT;
}
/*
* Enable and initialize the xsave feature.
*/
void __init xsave_cntxt_init(void)
{
unsigned int eax, ebx, ecx, edx;
cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx);
pcntxt_lmask = eax;
pcntxt_hmask = edx;
if ((pcntxt_lmask & XSTATE_FPSSE) != XSTATE_FPSSE) {
printk(KERN_ERR "FP/SSE not shown under xsave features %x\n",
pcntxt_lmask);
BUG();
}
/*
* for now OS knows only about FP/SSE
*/
pcntxt_lmask = pcntxt_lmask & XCNTXT_LMASK;
pcntxt_hmask = pcntxt_hmask & XCNTXT_HMASK;
xsave_init();
/*
* Recompute the context size for enabled features
*/
cpuid_count(0xd, 0, &eax, &ebx, &ecx, &edx);
xstate_size = ebx;
setup_xstate_init();
printk(KERN_INFO "xsave/xrstor: enabled xstate_bv 0x%Lx, "
"cntxt size 0x%x\n",
(pcntxt_lmask | ((u64) pcntxt_hmask << 32)), xstate_size);
}
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