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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] x86: use {rd, wr}{fs, gs}base when available
commit 4b46e7be783df641b2889e514e85643febd378c2
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Oct 11 09:30:31 2013 +0200
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Oct 11 09:30:31 2013 +0200
x86: use {rd,wr}{fs,gs}base when available
... as being intended to be faster than MSR reads/writes.
In the case of emulate_privileged_op() also use these in favor of the
cached (but possibly stale) addresses from arch.pv_vcpu. This allows
entirely removing the code that was the subject of XSA-67.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Acked-by: Keir Fraser <keir@xxxxxxx>
---
xen/arch/x86/Rules.mk | 1 +
xen/arch/x86/acpi/suspend.c | 8 +++---
xen/arch/x86/domain.c | 4 +-
xen/arch/x86/setup.c | 3 ++
xen/arch/x86/traps.c | 30 +++++++---------------
xen/include/asm-x86/domain.h | 6 ++--
xen/include/asm-x86/msr.h | 56 ++++++++++++++++++++++++++++++++++++++++++
7 files changed, 79 insertions(+), 29 deletions(-)
diff --git a/xen/arch/x86/Rules.mk b/xen/arch/x86/Rules.mk
index c93d2af..576985e 100644
--- a/xen/arch/x86/Rules.mk
+++ b/xen/arch/x86/Rules.mk
@@ -31,6 +31,7 @@ $(call cc-options-add,CFLAGS,CC,$(EMBEDDED_EXTRA_CFLAGS))
$(call cc-option-add,CFLAGS,CC,-Wnested-externs)
$(call as-insn-check,CFLAGS,CC,"vmcall",-DHAVE_GAS_VMX)
$(call as-insn-check,CFLAGS,CC,"invept (%rax)$$(comma)%rax",-DHAVE_GAS_EPT)
+$(call as-insn-check,CFLAGS,CC,"rdfsbase %rax",-DHAVE_GAS_FSGSBASE)
ifeq ($(supervisor_mode_kernel),y)
CFLAGS += -DCONFIG_X86_SUPERVISOR_MODE_KERNEL=1
diff --git a/xen/arch/x86/acpi/suspend.c b/xen/arch/x86/acpi/suspend.c
index c690b45..9c3cf38 100644
--- a/xen/arch/x86/acpi/suspend.c
+++ b/xen/arch/x86/acpi/suspend.c
@@ -27,8 +27,8 @@ void save_rest_processor_state(void)
asm volatile (
"movw %%ds,(%0); movw %%es,2(%0); movw %%fs,4(%0); movw %%gs,6(%0)"
: : "r" (saved_segs) : "memory" );
- rdmsrl(MSR_FS_BASE, saved_fs_base);
- rdmsrl(MSR_GS_BASE, saved_gs_base);
+ saved_fs_base = rdfsbase();
+ saved_gs_base = rdgsbase();
rdmsrl(MSR_SHADOW_GS_BASE, saved_kernel_gs_base);
rdmsrl(MSR_CSTAR, saved_cstar);
rdmsrl(MSR_LSTAR, saved_lstar);
@@ -56,8 +56,8 @@ void restore_rest_processor_state(void)
X86_EFLAGS_DF|X86_EFLAGS_IF|X86_EFLAGS_TF,
0U);
- wrmsrl(MSR_FS_BASE, saved_fs_base);
- wrmsrl(MSR_GS_BASE, saved_gs_base);
+ wrfsbase(saved_fs_base);
+ wrgsbase(saved_gs_base);
wrmsrl(MSR_SHADOW_GS_BASE, saved_kernel_gs_base);
if ( boot_cpu_data.x86_vendor == X86_VENDOR_INTEL ||
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 52b7a37..b67fcb8 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1092,7 +1092,7 @@ static void load_segments(struct vcpu *n)
{
/* This can only be non-zero if selector is NULL. */
if ( n->arch.pv_vcpu.fs_base )
- wrmsrl(MSR_FS_BASE, n->arch.pv_vcpu.fs_base);
+ wrfsbase(n->arch.pv_vcpu.fs_base);
/* Most kernels have non-zero GS base, so don't bother testing. */
/* (This is also a serialising instruction, avoiding AMD erratum #88.)
*/
@@ -1100,7 +1100,7 @@ static void load_segments(struct vcpu *n)
/* This can only be non-zero if selector is NULL. */
if ( n->arch.pv_vcpu.gs_base_user )
- wrmsrl(MSR_GS_BASE, n->arch.pv_vcpu.gs_base_user);
+ wrgsbase(n->arch.pv_vcpu.gs_base_user);
/* If in kernel mode then switch the GS bases around. */
if ( (n->arch.flags & TF_kernel_mode) )
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 637f1f9..30a4fd6 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1264,6 +1264,9 @@ void __init __start_xen(unsigned long mbi_p)
if ( cpu_has_smep )
set_in_cr4(X86_CR4_SMEP);
+ if ( cpu_has_fsgsbase )
+ set_in_cr4(X86_CR4_FSGSBASE);
+
local_irq_enable();
pt_pci_init();
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 35be017..8dcb70a 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -1985,28 +1985,18 @@ static int emulate_privileged_op(struct cpu_user_regs
*regs)
}
else
{
- if ( lm_ovr == lm_seg_none || data_sel < 4 )
+ switch ( lm_ovr )
{
- switch ( lm_ovr )
- {
- case lm_seg_none:
- data_base = 0UL;
- break;
- case lm_seg_fs:
- data_base = v->arch.pv_vcpu.fs_base;
- break;
- case lm_seg_gs:
- if ( guest_kernel_mode(v, regs) )
- data_base = v->arch.pv_vcpu.gs_base_kernel;
- else
- data_base = v->arch.pv_vcpu.gs_base_user;
- break;
- }
+ default:
+ data_base = 0UL;
+ break;
+ case lm_seg_fs:
+ data_base = rdfsbase();
+ break;
+ case lm_seg_gs:
+ data_base = rdgsbase();
+ break;
}
- else if ( !read_descriptor(data_sel, v, regs,
- &data_base, &data_limit, &ar, 0) ||
- !(ar & _SEGMENT_S) || !(ar & _SEGMENT_P) )
- goto fail;
data_limit = ~0UL;
ar = _SEGMENT_WR|_SEGMENT_S|_SEGMENT_DPL|_SEGMENT_P;
}
diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h
index 909f449..e42651e 100644
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -457,12 +457,12 @@ unsigned long pv_guest_cr4_fixup(const struct vcpu *,
unsigned long guest_cr4);
(((v)->arch.pv_vcpu.ctrlreg[4] \
| (mmu_cr4_features \
& (X86_CR4_PGE | X86_CR4_PSE | X86_CR4_SMEP | \
- X86_CR4_OSXSAVE)) \
+ X86_CR4_OSXSAVE | X86_CR4_FSGSBASE)) \
| ((v)->domain->arch.vtsc ? X86_CR4_TSD : 0)) \
& ~X86_CR4_DE)
#define real_cr4_to_pv_guest_cr4(c) \
- ((c) & ~(X86_CR4_PGE | X86_CR4_PSE | X86_CR4_TSD \
- | X86_CR4_OSXSAVE | X86_CR4_SMEP))
+ ((c) & ~(X86_CR4_PGE | X86_CR4_PSE | X86_CR4_TSD | \
+ X86_CR4_OSXSAVE | X86_CR4_SMEP | X86_CR4_FSGSBASE))
void domain_cpuid(struct domain *d,
unsigned int input,
diff --git a/xen/include/asm-x86/msr.h b/xen/include/asm-x86/msr.h
index 06c46a8..5277c2b 100644
--- a/xen/include/asm-x86/msr.h
+++ b/xen/include/asm-x86/msr.h
@@ -9,6 +9,7 @@
#include <xen/percpu.h>
#include <xen/errno.h>
#include <asm/asm_defns.h>
+#include <asm/cpufeature.h>
#define rdmsr(msr,val1,val2) \
__asm__ __volatile__("rdmsr" \
@@ -97,6 +98,61 @@ static inline int wrmsr_safe(unsigned int msr, uint64_t val)
: "=a" (low), "=d" (high) \
: "c" (counter))
+static inline unsigned long rdfsbase(void)
+{
+ unsigned long base;
+
+ if ( cpu_has_fsgsbase )
+#ifdef HAVE_GAS_FSGSBASE
+ asm volatile ( "rdfsbase %0" : "=r" (base) );
+#else
+ asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xc0" : "=a" (base) );
+#endif
+ else
+ rdmsrl(MSR_FS_BASE, base);
+
+ return base;
+}
+
+static inline unsigned long rdgsbase(void)
+{
+ unsigned long base;
+
+ if ( cpu_has_fsgsbase )
+#ifdef HAVE_GAS_FSGSBASE
+ asm volatile ( "rdgsbase %0" : "=r" (base) );
+#else
+ asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xc8" : "=a" (base) );
+#endif
+ else
+ rdmsrl(MSR_GS_BASE, base);
+
+ return base;
+}
+
+static inline void wrfsbase(unsigned long base)
+{
+ if ( cpu_has_fsgsbase )
+#ifdef HAVE_GAS_FSGSBASE
+ asm volatile ( "wrfsbase %0" :: "r" (base) );
+#else
+ asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xd0" :: "a" (base) );
+#endif
+ else
+ wrmsrl(MSR_FS_BASE, base);
+}
+
+static inline void wrgsbase(unsigned long base)
+{
+ if ( cpu_has_fsgsbase )
+#ifdef HAVE_GAS_FSGSBASE
+ asm volatile ( "wrgsbase %0" :: "r" (base) );
+#else
+ asm volatile ( ".byte 0xf3, 0x48, 0x0f, 0xae, 0xd8" :: "a" (base) );
+#endif
+ else
+ wrmsrl(MSR_GS_BASE, base);
+}
DECLARE_PER_CPU(u64, efer);
u64 read_efer(void);
--
generated by git-patchbot for /home/xen/git/xen.git#master
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