x86, xsave: enable xsave/xrstor on cpus with xsave support
Enables xsave/xrstor by turning on cr4.osxsave on cpu's which have
the xsave support. For now, features that OS supports/enabled are
FP and SSE.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index a07ec14..d6ea91a 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -38,7 +38,7 @@
obj-$(CONFIG_X86_TRAMPOLINE) += trampoline.o
obj-y += process.o
-obj-y += i387.o
+obj-y += i387.o xsave.o
obj-y += ptrace.o
obj-y += ds.o
obj-$(CONFIG_X86_32) += tls.o
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 80ab20d..fabbcb7 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -712,6 +712,14 @@
current_thread_info()->status = 0;
clear_used_math();
mxcsr_feature_mask_init();
+
+ /*
+ * Boot processor to setup the FP and extended state context info.
+ */
+ if (!smp_processor_id())
+ init_thread_xstate();
+
+ xsave_init();
}
#ifdef CONFIG_HOTPLUG_CPU
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index eb9ddd8..e22a9a9 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -61,6 +61,11 @@
return;
}
+ if (cpu_has_xsave) {
+ xsave_cntxt_init();
+ return;
+ }
+
if (cpu_has_fxsr)
xstate_size = sizeof(struct i387_fxsave_struct);
#ifdef CONFIG_X86_32
@@ -83,6 +88,13 @@
write_cr0(oldcr0 & ~(X86_CR0_TS|X86_CR0_EM)); /* clear TS and EM */
+ /*
+ * Boot processor to setup the FP and extended state context info.
+ */
+ if (!smp_processor_id())
+ init_thread_xstate();
+ xsave_init();
+
mxcsr_feature_mask_init();
/* clean state in init */
current_thread_info()->status = 0;
diff --git a/arch/x86/kernel/traps_32.c b/arch/x86/kernel/traps_32.c
index 03df8e4..da5a596 100644
--- a/arch/x86/kernel/traps_32.c
+++ b/arch/x86/kernel/traps_32.c
@@ -1228,7 +1228,6 @@
set_bit(SYSCALL_VECTOR, used_vectors);
- init_thread_xstate();
/*
* Should be a barrier for any external CPU state:
*/
diff --git a/arch/x86/kernel/traps_64.c b/arch/x86/kernel/traps_64.c
index 513caac..3580a79 100644
--- a/arch/x86/kernel/traps_64.c
+++ b/arch/x86/kernel/traps_64.c
@@ -1173,10 +1173,6 @@
set_system_gate(IA32_SYSCALL_VECTOR, ia32_syscall);
#endif
/*
- * initialize the per thread extended state:
- */
- init_thread_xstate();
- /*
* Should be a barrier for any external CPU state:
*/
cpu_init();
diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c
new file mode 100644
index 0000000..c68b7c4
--- /dev/null
+++ b/arch/x86/kernel/xsave.c
@@ -0,0 +1,87 @@
+/*
+ * 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);
+}