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