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Limit the maximum number of back-to-back iterations of a "rep; ins/outs"

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to 16. This is arbitrary and is used to ensure that a vcpu goes back into
the vm_run() loop to process interrupts or rendezvous events in a timely
fashion.

Found with:	Coverity Scan
CID:		1216436
This commit is contained in:
Neel Natu 2014-06-01 02:13:07 +00:00
parent 95ebc360ef
commit 0be3798af5
1 changed files with 11 additions and 3 deletions
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14
usr.sbin/bhyve/inout.c
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@ -55,6 +55,10 @@ SET_DECLARE(inout_port_set, struct inout_port);
#define VERIFY_IOPORT(port, size) \
assert((port) >= 0 && (size) > 0 && ((port) + (size)) <= MAX_IOPORTS)
#ifndef min
#define min(a, b) ((a) < (b) ? (a) : (b))
#endif
static struct {
const char *name;
int flags;
@ -109,7 +113,7 @@ emulate_inout(struct vmctx *ctx, int vcpu, struct vm_exit *vmexit, int strict)
void *arg;
int error, retval;
enum vm_reg_name idxreg;
uint64_t gla, index, count;
uint64_t gla, index, iterations, count;
struct vm_inout_str *vis;
struct iovec iov[2];
@ -151,14 +155,17 @@ emulate_inout(struct vmctx *ctx, int vcpu, struct vm_exit *vmexit, int strict)
/* Count register */
count = vis->count & vie_size2mask(addrsize);
while (count) {
/* Limit number of back-to-back in/out emulations to 16 */
iterations = min(count, 16);
while (iterations > 0) {
if (vie_calculate_gla(vis->paging.cpu_mode,
vis->seg_name, &vis->seg_desc, index, bytes,
addrsize, prot, &gla)) {
error = vm_inject_exception2(ctx, vcpu,
IDT_GP, 0);
assert(error == 0);
return (INOUT_RESTART);
retval = INOUT_RESTART;
break;
}
error = vm_gla2gpa(ctx, vcpu, &vis->paging, gla, bytes,
@ -196,6 +203,7 @@ emulate_inout(struct vmctx *ctx, int vcpu, struct vm_exit *vmexit, int strict)
index += bytes;
count--;
iterations--;
}
/* Update index register */