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authorJeremy Fitzhardinge <jeremy@goop.org>2008-03-17 16:37:17 -0700
committerIngo Molnar <mingo@elte.hu>2008-04-24 23:57:31 +0200
commite2a81baf6604a2e08e10c7405b0349106f77c8af (patch)
tree3eaf386316be1f499d92fae213493ec3d6b5b576 /arch/x86
parentaa380c82b83252754a8c11bfc92359bd87cbf710 (diff)
xen: support sysenter/sysexit if hypervisor does
64-bit Xen supports sysenter for 32-bit guests, so support its use. (sysenter is faster than int $0x80 in 32-on-64.) sysexit is still not supported, so we fake it up using iret. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kernel/entry_32.S18
-rw-r--r--arch/x86/xen/enlighten.c3
-rw-r--r--arch/x86/xen/setup.c21
-rw-r--r--arch/x86/xen/smp.c1
-rw-r--r--arch/x86/xen/xen-asm.S56
-rw-r--r--arch/x86/xen/xen-ops.h3
6 files changed, 99 insertions, 3 deletions
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 568c6ccd7ae..5d80d53eaff 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1017,6 +1017,13 @@ ENTRY(kernel_thread_helper)
ENDPROC(kernel_thread_helper)
#ifdef CONFIG_XEN
+/* Xen doesn't set %esp to be precisely what the normal sysenter
+ entrypoint expects, so fix it up before using the normal path. */
+ENTRY(xen_sysenter_target)
+ RING0_INT_FRAME
+ addl $5*4, %esp /* remove xen-provided frame */
+ jmp sysenter_past_esp
+
ENTRY(xen_hypervisor_callback)
CFI_STARTPROC
pushl $0
@@ -1036,8 +1043,17 @@ ENTRY(xen_hypervisor_callback)
jae 1f
call xen_iret_crit_fixup
+ jmp 2f
+
+1: cmpl $xen_sysexit_start_crit,%eax
+ jb 2f
+ cmpl $xen_sysexit_end_crit,%eax
+ jae 2f
+
+ jmp xen_sysexit_crit_fixup
-1: mov %esp, %eax
+ENTRY(xen_do_upcall)
+2: mov %esp, %eax
call xen_evtchn_do_upcall
jmp ret_from_intr
CFI_ENDPROC
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 36f36e6b087..943684566eb 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -155,7 +155,6 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
if (*ax == 1)
maskedx = ~((1 << X86_FEATURE_APIC) | /* disable APIC */
(1 << X86_FEATURE_ACPI) | /* disable ACPI */
- (1 << X86_FEATURE_SEP) | /* disable SEP */
(1 << X86_FEATURE_ACC)); /* thermal monitoring */
asm(XEN_EMULATE_PREFIX "cpuid"
@@ -994,7 +993,7 @@ static const struct pv_cpu_ops xen_cpu_ops __initdata = {
.read_pmc = native_read_pmc,
.iret = xen_iret,
- .irq_enable_syscall_ret = NULL, /* never called */
+ .irq_enable_syscall_ret = xen_sysexit,
.load_tr_desc = paravirt_nop,
.set_ldt = xen_set_ldt,
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 2341492bf7a..82517e4a752 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -16,6 +16,7 @@
#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>
+#include <xen/interface/callback.h>
#include <xen/interface/physdev.h>
#include <xen/features.h>
@@ -68,6 +69,24 @@ static void __init fiddle_vdso(void)
*mask |= 1 << VDSO_NOTE_NONEGSEG_BIT;
}
+void xen_enable_sysenter(void)
+{
+ int cpu = smp_processor_id();
+ extern void xen_sysenter_target(void);
+ /* Mask events on entry, even though they get enabled immediately */
+ static struct callback_register sysenter = {
+ .type = CALLBACKTYPE_sysenter,
+ .address = { __KERNEL_CS, (unsigned long)xen_sysenter_target },
+ .flags = CALLBACKF_mask_events,
+ };
+
+ if (!boot_cpu_has(X86_FEATURE_SEP) ||
+ HYPERVISOR_callback_op(CALLBACKOP_register, &sysenter) != 0) {
+ clear_cpu_cap(&cpu_data(cpu), X86_FEATURE_SEP);
+ clear_cpu_cap(&boot_cpu_data, X86_FEATURE_SEP);
+ }
+}
+
void __init xen_arch_setup(void)
{
struct physdev_set_iopl set_iopl;
@@ -82,6 +101,8 @@ void __init xen_arch_setup(void)
HYPERVISOR_set_callbacks(__KERNEL_CS, (unsigned long)xen_hypervisor_callback,
__KERNEL_CS, (unsigned long)xen_failsafe_callback);
+ xen_enable_sysenter();
+
set_iopl.iopl = 1;
rc = HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl, &set_iopl);
if (rc != 0)
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index e340ff92f6b..d61e4f8b07c 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -72,6 +72,7 @@ static __cpuinit void cpu_bringup_and_idle(void)
int cpu = smp_processor_id();
cpu_init();
+ xen_enable_sysenter();
preempt_disable();
per_cpu(cpu_state, cpu) = CPU_ONLINE;
diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S
index 99223cc323b..1ac08082a4b 100644
--- a/arch/x86/xen/xen-asm.S
+++ b/arch/x86/xen/xen-asm.S
@@ -280,6 +280,62 @@ ENTRY(xen_iret_crit_fixup)
2: ret
+ENTRY(xen_sysexit)
+ /* Store vcpu_info pointer for easy access. Do it this
+ way to avoid having to reload %fs */
+#ifdef CONFIG_SMP
+ GET_THREAD_INFO(%eax)
+ movl TI_cpu(%eax),%eax
+ movl __per_cpu_offset(,%eax,4),%eax
+ mov per_cpu__xen_vcpu(%eax),%eax
+#else
+ movl per_cpu__xen_vcpu, %eax
+#endif
+
+ /* We can't actually use sysexit in a pv guest,
+ so fake it up with iret */
+ pushl $__USER_DS /* user stack segment */
+ pushl %ecx /* user esp */
+ pushl PT_EFLAGS+2*4(%esp) /* user eflags */
+ pushl $__USER_CS /* user code segment */
+ pushl %edx /* user eip */
+
+xen_sysexit_start_crit:
+ /* Unmask events... */
+ movb $0, XEN_vcpu_info_mask(%eax)
+ /* ...and test for pending.
+ There's a preempt window here, but it doesn't
+ matter because we're within the critical section. */
+ testb $0xff, XEN_vcpu_info_pending(%eax)
+
+ /* If there's something pending, mask events again so we
+ can directly inject it back into the kernel. */
+ jnz 1f
+
+ movl PT_EAX+5*4(%esp),%eax
+2: iret
+1: movb $1, XEN_vcpu_info_mask(%eax)
+xen_sysexit_end_crit:
+ addl $5*4, %esp /* remove iret frame */
+ /* no need to re-save regs, but need to restore kernel %fs */
+ mov $__KERNEL_PERCPU, %eax
+ mov %eax, %fs
+ jmp xen_do_upcall
+.section __ex_table,"a"
+ .align 4
+ .long 2b,iret_exc
+.previous
+
+ .globl xen_sysexit_start_crit, xen_sysexit_end_crit
+/*
+ sysexit fixup is easy, since the old frame is still sitting there
+ on the stack. We just need to remove the new recursive
+ interrupt and return.
+ */
+ENTRY(xen_sysexit_crit_fixup)
+ addl $PT_OLDESP+5*4, %esp /* remove frame+iret */
+ jmp xen_do_upcall
+
/*
Force an event check by making a hypercall,
but preserve regs before making the call.
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 956a491ea99..01d4ff2ce40 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -19,6 +19,7 @@ extern struct shared_info *HYPERVISOR_shared_info;
char * __init xen_memory_setup(void);
void __init xen_arch_setup(void);
void __init xen_init_IRQ(void);
+void xen_enable_sysenter(void);
void xen_setup_timer(int cpu);
void xen_setup_cpu_clockevents(void);
@@ -64,4 +65,6 @@ DECL_ASM(unsigned long, xen_save_fl_direct, void);
DECL_ASM(void, xen_restore_fl_direct, unsigned long);
void xen_iret(void);
+void xen_sysexit(void);
+
#endif /* XEN_OPS_H */