xen: support sysenter/sysexit if hypervisor does (e2a81baf) · Commits · 戴 / test

arch/x86/kernel/entry_32.S

+17 −1

Original line number	Diff line number	Diff line
		@@ -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 $54, %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

arch/x86/xen/enlighten.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -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,

arch/x86/xen/setup.c

+21 −0

Original line number	Diff line number	Diff line
		@@ -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)

arch/x86/xen/smp.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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;

arch/x86/xen/xen-asm.S

+56 −0

Original line number	Diff line number	Diff line
		@@ -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+24(%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 $54, %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+54, %esp / remove frame+iret */
		jmp xen_do_upcall

		/*
		Force an event check by making a hypercall,
		but preserve regs before making the call.

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