The sense of the IF bit is backwards in the host interrupt handling.
This means we always save "IF=1" on the stack when injecting an
interrupt. It turns out this is almost always correct (unless the
guest is taking a page fault in an interrupt due to an unpopulated
vmalloc mapping), so went unnoticed.
Signed-off-by: Rusty Russell <[email protected]>
---
drivers/lguest/interrupts_and_traps.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff -r 209f5cd5cda5 drivers/lguest/interrupts_and_traps.c
--- a/drivers/lguest/interrupts_and_traps.c Fri Jul 20 14:53:40 2007 +1000
+++ b/drivers/lguest/interrupts_and_traps.c Fri Jul 20 21:34:06 2007 +1000
@@ -38,12 +38,12 @@ static void set_guest_interrupt(struct l
ss = lg->regs->ss;
}
- /* We use IF bit in eflags to indicate whether irqs were disabled
- (it's always 0, since irqs are enabled when guest is running). */
+ /* We use IF bit in eflags to indicate whether irqs were enabled
+ (it's always 1, since irqs are enabled when guest is running). */
eflags = lg->regs->eflags;
- if (get_user(irq_enable, &lg->lguest_data->irq_enabled))
- irq_enable = 0;
- eflags |= (irq_enable & X86_EFLAGS_IF);
+ if (get_user(irq_enable, &lg->lguest_data->irq_enabled) == 0
+ && !(irq_enable & X86_EFLAGS_IF))
+ eflags &= ~X86_EFLAGS_IF;
push_guest_stack(lg, &gstack, eflags);
push_guest_stack(lg, &gstack, lg->regs->cs);
-
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