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ab234a260b
POPF is a rather expensive operation, so don't use it for restoring irq flags. Instead, test whether interrupts are enabled in the flags parameter and enable interrupts via STI in that case. This results in the restore_fl paravirt op to be no longer needed. Suggested-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20210120135555.32594-7-jgross@suse.com
111 lines
2.6 KiB
C
111 lines
2.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/hardirq.h>
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#include <asm/x86_init.h>
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#include <xen/interface/xen.h>
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#include <xen/interface/sched.h>
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#include <xen/interface/vcpu.h>
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#include <xen/features.h>
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#include <xen/events.h>
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#include <asm/xen/hypercall.h>
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#include <asm/xen/hypervisor.h>
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#include "xen-ops.h"
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/*
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* Force a proper event-channel callback from Xen after clearing the
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* callback mask. We do this in a very simple manner, by making a call
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* down into Xen. The pending flag will be checked by Xen on return.
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*/
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void xen_force_evtchn_callback(void)
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{
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(void)HYPERVISOR_xen_version(0, NULL);
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}
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asmlinkage __visible unsigned long xen_save_fl(void)
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{
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struct vcpu_info *vcpu;
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unsigned long flags;
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vcpu = this_cpu_read(xen_vcpu);
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/* flag has opposite sense of mask */
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flags = !vcpu->evtchn_upcall_mask;
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/* convert to IF type flag
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-0 -> 0x00000000
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-1 -> 0xffffffff
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*/
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return (-flags) & X86_EFLAGS_IF;
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}
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PV_CALLEE_SAVE_REGS_THUNK(xen_save_fl);
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asmlinkage __visible void xen_irq_disable(void)
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{
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/* There's a one instruction preempt window here. We need to
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make sure we're don't switch CPUs between getting the vcpu
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pointer and updating the mask. */
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preempt_disable();
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this_cpu_read(xen_vcpu)->evtchn_upcall_mask = 1;
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preempt_enable_no_resched();
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}
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PV_CALLEE_SAVE_REGS_THUNK(xen_irq_disable);
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asmlinkage __visible void xen_irq_enable(void)
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{
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struct vcpu_info *vcpu;
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/*
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* We may be preempted as soon as vcpu->evtchn_upcall_mask is
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* cleared, so disable preemption to ensure we check for
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* events on the VCPU we are still running on.
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*/
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preempt_disable();
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vcpu = this_cpu_read(xen_vcpu);
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vcpu->evtchn_upcall_mask = 0;
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/* Doesn't matter if we get preempted here, because any
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pending event will get dealt with anyway. */
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barrier(); /* unmask then check (avoid races) */
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if (unlikely(vcpu->evtchn_upcall_pending))
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xen_force_evtchn_callback();
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preempt_enable();
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}
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PV_CALLEE_SAVE_REGS_THUNK(xen_irq_enable);
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static void xen_safe_halt(void)
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{
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/* Blocking includes an implicit local_irq_enable(). */
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if (HYPERVISOR_sched_op(SCHEDOP_block, NULL) != 0)
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BUG();
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}
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static void xen_halt(void)
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{
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if (irqs_disabled())
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HYPERVISOR_vcpu_op(VCPUOP_down,
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xen_vcpu_nr(smp_processor_id()), NULL);
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else
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xen_safe_halt();
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}
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static const struct pv_irq_ops xen_irq_ops __initconst = {
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.save_fl = PV_CALLEE_SAVE(xen_save_fl),
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.irq_disable = PV_CALLEE_SAVE(xen_irq_disable),
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.irq_enable = PV_CALLEE_SAVE(xen_irq_enable),
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.safe_halt = xen_safe_halt,
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.halt = xen_halt,
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};
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void __init xen_init_irq_ops(void)
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{
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pv_ops.irq = xen_irq_ops;
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x86_init.irqs.intr_init = xen_init_IRQ;
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}
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