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authorRusty Russell <rusty@rustcorp.com.au>2016-04-01 12:15:46 +1030
committerIngo Molnar <mingo@kernel.org>2016-04-01 08:58:13 +0200
commitf87e0434a3bedeb5e4d75d96d9f3ad424dae6b33 (patch)
treeaa18b1303e0082c527e5fad3b4d43631cd0d4fb1 /drivers/lguest/lg.h
parent6d92bc9d483aa1751755a66fee8fb39dffb088c0 (diff)
downloadlinux-f87e0434a3bedeb5e4d75d96d9f3ad424dae6b33.tar.bz2
lguest, x86/entry/32: Fix handling of guest syscalls using interrupt gates
In a798f091113e ("x86/entry/32: Change INT80 to be an interrupt gate") Andy broke lguest. This is because lguest had special code to allow the 0x80 trap gate go straight into the guest itself; interrupts gates (without more work, as mentioned in the file's comments) bounce via the hypervisor. His change made them go via the hypervisor, but as it's in the range of normal hardware interrupts, they were not directed through to the guest at all. Turns out the guest userspace isn't very effective if syscalls are all noops. I haven't ripped out all the now-useless trap-direct-to-guest-kernel code yet, since it will still be needed if someone decides to update this optimization. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Weisbecker <fweisbec@gmail.com> Cc: x86\@kernel.org Link: http://lkml.kernel.org/r/87fuv685kl.fsf@rustcorp.com.au Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'drivers/lguest/lg.h')
-rw-r--r--drivers/lguest/lg.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index ac8ad0461e80..69b3814afd2f 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -167,6 +167,7 @@ void guest_set_clockevent(struct lg_cpu *cpu, unsigned long delta);
bool send_notify_to_eventfd(struct lg_cpu *cpu);
void init_clockdev(struct lg_cpu *cpu);
bool check_syscall_vector(struct lguest *lg);
+bool could_be_syscall(unsigned int num);
int init_interrupts(void);
void free_interrupts(void);