Jan Beulich
2010-Oct-22 13:30 UTC
[Xen-devel] [PATCH] x86: enable support for {rd,wr}{fs,gs}base instructions
... so that once in a while Xen knows of a new CPU feature before Linux
starts making use of it.
While (obviously) I wasn''t able to test this, it seemed strait forward
enough to enable anyway.
Signed-off-by: Jan Beulich <jbeulich@novell.com>
--- 2010-10-22.orig/xen/arch/x86/cpu/common.c 2010-08-06 08:44:33.000000000
+0200
+++ 2010-10-22/xen/arch/x86/cpu/common.c 2010-10-22 13:53:59.000000000 +0200
@@ -311,6 +311,11 @@ void __cpuinit generic_identify(struct c
if ( xlvl >= 0x80000004 )
get_model_name(c); /* Default name */
}
+
+ /* Intel-defined flags: level 0x00000007 */
+ if ( c->cpuid_level >= 0x00000007 )
+ c->x86_capability[X86_FEATURE_FSGSBASE / 32]
+ = cpuid_ebx(0x00000007);
}
early_intel_workaround(c);
--- 2010-10-22.orig/xen/arch/x86/domain.c 2010-08-12 08:17:22.000000000 +0200
+++ 2010-10-22/xen/arch/x86/domain.c 2010-10-22 13:53:59.000000000 +0200
@@ -583,13 +583,15 @@ void arch_domain_destroy(struct domain *
xfree(d->arch.irq_pirq);
}
-unsigned long pv_guest_cr4_fixup(unsigned long guest_cr4)
+unsigned long pv_guest_cr4_fixup(const struct vcpu *v, unsigned long guest_cr4)
{
unsigned long hv_cr4_mask, hv_cr4 = real_cr4_to_pv_guest_cr4(read_cr4());
hv_cr4_mask = ~X86_CR4_TSD;
if ( cpu_has_de )
hv_cr4_mask &= ~X86_CR4_DE;
+ if ( cpu_has_fsgsbase && !is_pv_32bit_domain(v->domain) )
+ hv_cr4_mask &= ~X86_CR4_FSGSBASE;
if ( (guest_cr4 & hv_cr4_mask) != (hv_cr4 & hv_cr4_mask) )
gdprintk(XENLOG_WARNING,
@@ -700,7 +702,7 @@ int arch_set_info_guest(
v->arch.guest_context.user_regs.eflags |= X86_EFLAGS_IF;
cr4 = v->arch.guest_context.ctrlreg[4];
- v->arch.guest_context.ctrlreg[4] = cr4 ? pv_guest_cr4_fixup(cr4) :
+ v->arch.guest_context.ctrlreg[4] = cr4 ? pv_guest_cr4_fixup(v, cr4) :
real_cr4_to_pv_guest_cr4(mmu_cr4_features);
memset(v->arch.guest_context.debugreg, 0,
--- 2010-10-22.orig/xen/arch/x86/traps.c 2010-10-15 11:02:30.000000000 +0200
+++ 2010-10-22/xen/arch/x86/traps.c 2010-10-22 13:53:59.000000000 +0200
@@ -2176,7 +2176,7 @@ static int emulate_privileged_op(struct
break;
case 4: /* Write CR4 */
- v->arch.guest_context.ctrlreg[4] = pv_guest_cr4_fixup(*reg);
+ v->arch.guest_context.ctrlreg[4] = pv_guest_cr4_fixup(v, *reg);
write_cr4(pv_guest_cr4_to_real_cr4(v));
break;
--- 2010-10-22.orig/xen/include/asm-x86/cpufeature.h 2010-10-22
13:51:12.000000000 +0200
+++ 2010-10-22/xen/include/asm-x86/cpufeature.h 2010-10-22 13:53:59.000000000
+0200
@@ -9,7 +9,7 @@
#include <xen/bitops.h>
-#define NCAPINTS 7 /* N 32-bit words worth of info */
+#define NCAPINTS 8 /* N 32-bit words worth of info */
/* Intel-defined CPU features, CPUID level 0x00000001 (edx), word 0 */
#define X86_FEATURE_FPU (0*32+ 0) /* Onboard FPU */
@@ -131,6 +131,9 @@
#define X86_FEATURE_SKINIT (6*32+ 12) /* SKINIT, STGI/CLGI, DEV */
#define X86_FEATURE_WDT (6*32+ 13) /* Watchdog Timer */
+/* Intel-defined CPU features, CPUID level 0x00000007:0 (ebx), word 9 */
+#define X86_FEATURE_FSGSBASE (7*32+ 0) /* {RD,WR}{FS,GS}BASE instructions */
+
#define cpu_has(c, bit) test_bit(bit, (c)->x86_capability)
#define boot_cpu_has(bit) test_bit(bit, boot_cpu_data.x86_capability)
@@ -159,6 +162,7 @@
#define cpu_has_clflush boot_cpu_has(X86_FEATURE_CLFLSH)
#define cpu_has_page1gb 0
#define cpu_has_efer (boot_cpu_data.x86_capability[1] & 0x20100800)
+#define cpu_has_fsgsbase 0
#else /* __x86_64__ */
#define cpu_has_vme 0
#define cpu_has_de 1
@@ -184,6 +188,7 @@
#define cpu_has_clflush boot_cpu_has(X86_FEATURE_CLFLSH)
#define cpu_has_page1gb boot_cpu_has(X86_FEATURE_PAGE1GB)
#define cpu_has_efer 1
+#define cpu_has_fsgsbase boot_cpu_has(X86_FEATURE_FSGSBASE)
#endif
#define cpu_has_ffxsr ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) \
--- 2010-10-22.orig/xen/include/asm-x86/domain.h 2010-09-06 08:21:15.000000000
+0200
+++ 2010-10-22/xen/include/asm-x86/domain.h 2010-10-22 13:53:59.000000000 +0200
@@ -429,7 +429,7 @@ void vcpu_show_execution_state(struct vc
void vcpu_show_registers(const struct vcpu *);
/* Clean up CR4 bits that are not under guest control. */
-unsigned long pv_guest_cr4_fixup(unsigned long guest_cr4);
+unsigned long pv_guest_cr4_fixup(const struct vcpu *, unsigned long guest_cr4);
/* Convert between guest-visible and real CR4 values. */
#define pv_guest_cr4_to_real_cr4(v) \
--- 2010-10-22.orig/xen/include/asm-x86/processor.h 2010-10-22
10:59:09.000000000 +0200
+++ 2010-10-22/xen/include/asm-x86/processor.h 2010-10-22 13:53:59.000000000
+0200
@@ -83,6 +83,7 @@
#define X86_CR4_OSXMMEXCPT 0x0400 /* enable unmasked SSE exceptions */
#define X86_CR4_VMXE 0x2000 /* enable VMX */
#define X86_CR4_SMXE 0x4000 /* enable SMX */
+#define X86_CR4_FSGSBASE 0x10000 /* enable {rd,wr}{fs,gs}base */
#define X86_CR4_OSXSAVE 0x40000 /* enable XSAVE/XRSTOR */
/*
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