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Don't pass the 'error' return from an I/O port handler directly to vm_run().

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Most I/O port handlers return -1 to signal an error. If this value is returned
without modification to vm_run() then it leads to incorrect behavior because
'-1' is interpreted as ERESTART at the system call level.

Fix this by always returning EIO to signal an error from an I/O port handler.

MFC after:	1 week
This commit is contained in:
Neel Natu 2014-10-26 03:03:41 +00:00
parent f84f8f9468
commit 31b117bec9
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=273666
1 changed files with 28 additions and 22 deletions
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50
sys/amd64/vmm/vmm_ioport.c
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@ -106,15 +106,14 @@ emulate_inout_port(struct vm *vm, int vcpuid, struct vm_exit *vmexit,
uint32_t mask, val;
int error;
error = 0;
*retu = true;
if (vmexit->u.inout.port >= MAX_IOPORTS)
goto done;
handler = ioport_handler[vmexit->u.inout.port];
if (handler == NULL)
goto done;
/*
* If there is no handler for the I/O port then punt to userspace.
*/
if (vmexit->u.inout.port >= MAX_IOPORTS ||
(handler = ioport_handler[vmexit->u.inout.port]) == NULL) {
*retu = true;
return (0);
}
mask = vie_size2mask(vmexit->u.inout.bytes);
@ -124,20 +123,27 @@ emulate_inout_port(struct vm *vm, int vcpuid, struct vm_exit *vmexit,
error = (*handler)(vm, vcpuid, vmexit->u.inout.in,
vmexit->u.inout.port, vmexit->u.inout.bytes, &val);
if (!error) {
*retu = false;
if (vmexit->u.inout.in) {
vmexit->u.inout.eax &= ~mask;
vmexit->u.inout.eax |= val & mask;
error = vm_set_register(vm, vcpuid,
VM_REG_GUEST_RAX, vmexit->u.inout.eax);
KASSERT(error == 0, ("emulate_ioport: error %d "
"setting guest rax register", error));
}
if (error) {
/*
* The value returned by this function is also the return value
* of vm_run(). This needs to be a positive number otherwise it
* can be interpreted as a "pseudo-error" like ERESTART.
*
* Enforce this by mapping all errors to EIO.
*/
return (EIO);
}
done:
return (error);
if (vmexit->u.inout.in) {
vmexit->u.inout.eax &= ~mask;
vmexit->u.inout.eax |= val & mask;
error = vm_set_register(vm, vcpuid, VM_REG_GUEST_RAX,
vmexit->u.inout.eax);
KASSERT(error == 0, ("emulate_ioport: error %d setting guest "
"rax register", error));
}
*retu = false;
return (0);
}
static int