From a76d8ee4e9b6e0f73c4210907a7f9773ca25c154 Mon Sep 17 00:00:00 2001 From: neel Date: Sun, 26 Oct 2014 03:03:41 +0000 Subject: Don't pass the 'error' return from an I/O port handler directly to vm_run(). 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 --- sys/amd64/vmm/vmm_ioport.c | 48 ++++++++++++++++++++++++++-------------------- 1 file changed, 27 insertions(+), 21 deletions(-) (limited to 'sys/amd64/vmm') diff --git a/sys/amd64/vmm/vmm_ioport.c b/sys/amd64/vmm/vmm_ioport.c index 4ce1403..564ca74 100644 --- a/sys/amd64/vmm/vmm_ioport.c +++ b/sys/amd64/vmm/vmm_ioport.c @@ -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) { + /* + * 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); + } - 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 (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)); } -done: - return (error); + *retu = false; + return (0); } static int -- cgit v1.1