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Commit e5faff45 authored by Rusty Russell's avatar Rusty Russell Committed by Linus Torvalds
Browse files

lguest: fix sense if IF flag on interrupt injection 



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: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent bd6dc742

drivers/lguest/interrupts_and_traps.c

+5 −5
Original line number Diff line number Diff line
@@ -38,12 +38,12 @@ static void set_guest_interrupt(struct lguest *lg, u32 lo, u32 hi, int has_err) 
		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);