Revision 0447378a4a793da008451fad50bc0f93e9675ae6 authored by Marc Orr on 21 June 2018, 00:21:29 UTC, committed by Radim Krčmář on 22 June 2018, 14:46:26 UTC
This patch extends the checks done prior to a nested VM entry. Specifically, it extends the check_vmentry_prereqs function with checks for fields relevant to the VM-entry event injection information, as described in the Intel SDM, volume 3. This patch is motivated by a syzkaller bug, where a bad VM-entry interruption information field is generated in the VMCS02, which causes the nested VM launch to fail. Then, KVM fails to resume L1. While KVM should be improved to correctly resume L1 execution after a failed nested launch, this change is justified because the existing code to resume L1 is flaky/ad-hoc and the test coverage for resuming L1 is sparse. Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Marc Orr <marcorr@google.com> [Removed comment whose parts were describing previous revisions and the rest was obvious from function/variable naming. - Radim] Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
1 parent 5f9077c
resend.c
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
* Copyright (C) 2005-2006, Thomas Gleixner
*
* This file contains the IRQ-resend code
*
* If the interrupt is waiting to be processed, we try to re-run it.
* We can't directly run it from here since the caller might be in an
* interrupt-protected region. Not all irq controller chips can
* retrigger interrupts at the hardware level, so in those cases
* we allow the resending of IRQs via a tasklet.
*/
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/interrupt.h>
#include "internals.h"
#ifdef CONFIG_HARDIRQS_SW_RESEND
/* Bitmap to handle software resend of interrupts: */
static DECLARE_BITMAP(irqs_resend, IRQ_BITMAP_BITS);
/*
* Run software resends of IRQ's
*/
static void resend_irqs(unsigned long arg)
{
struct irq_desc *desc;
int irq;
while (!bitmap_empty(irqs_resend, nr_irqs)) {
irq = find_first_bit(irqs_resend, nr_irqs);
clear_bit(irq, irqs_resend);
desc = irq_to_desc(irq);
local_irq_disable();
desc->handle_irq(desc);
local_irq_enable();
}
}
/* Tasklet to handle resend: */
static DECLARE_TASKLET(resend_tasklet, resend_irqs, 0);
#endif
/*
* IRQ resend
*
* Is called with interrupts disabled and desc->lock held.
*/
void check_irq_resend(struct irq_desc *desc)
{
/*
* We do not resend level type interrupts. Level type
* interrupts are resent by hardware when they are still
* active. Clear the pending bit so suspend/resume does not
* get confused.
*/
if (irq_settings_is_level(desc)) {
desc->istate &= ~IRQS_PENDING;
return;
}
if (desc->istate & IRQS_REPLAY)
return;
if (desc->istate & IRQS_PENDING) {
desc->istate &= ~IRQS_PENDING;
desc->istate |= IRQS_REPLAY;
if (!desc->irq_data.chip->irq_retrigger ||
!desc->irq_data.chip->irq_retrigger(&desc->irq_data)) {
#ifdef CONFIG_HARDIRQS_SW_RESEND
unsigned int irq = irq_desc_get_irq(desc);
/*
* If the interrupt is running in the thread
* context of the parent irq we need to be
* careful, because we cannot trigger it
* directly.
*/
if (irq_settings_is_nested_thread(desc)) {
/*
* If the parent_irq is valid, we
* retrigger the parent, otherwise we
* do nothing.
*/
if (!desc->parent_irq)
return;
irq = desc->parent_irq;
}
/* Set it pending and activate the softirq: */
set_bit(irq, irqs_resend);
tasklet_schedule(&resend_tasklet);
#endif
}
}
}
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