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bhyve: virtio-net: disable receive until features are negotiated

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This patch fixes a race condition where the receive callback is called
while the device is being reset. Since the rx_merge variable may change
during reset, the receive callback may operate inconsistently with what
the guest expects.
Also, get rid of the unused rx_vhdrlen variable.

PR:	242023
Reported by:	aleksandr.fedorov@itglobal.com
Reviewed by:	markj, jhb
MFC with:	r354552
Differential Revision:	https://reviews.freebsd.org/D22440
This commit is contained in:
vmaffione 2019-11-19 21:10:44 +00:00
parent 79837b3c5e
commit 9efa1d846d
1 changed files with 22 additions and 11 deletions
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33
usr.sbin/bhyve/pci_virtio_net.c
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@ -109,7 +109,6 @@ struct pci_vtnet_softc {
uint64_t vsc_features; /* negotiated features */
pthread_mutex_t rx_mtx;
unsigned int rx_vhdrlen;
int rx_merge; /* merged rx bufs in use */
pthread_t tx_tid;
@ -149,6 +148,16 @@ pci_vtnet_reset(void *vsc)
/* Acquire the RX lock to block RX processing. */
pthread_mutex_lock(&sc->rx_mtx);
/*
* Make sure receive operation is disabled at least until we
* re-negotiate the features, since receive operation depends
* on the value of sc->rx_merge and the header length, which
* are both set in pci_vtnet_neg_features().
* Receive operation will be enabled again once the guest adds
* the first receive buffers and kicks us.
*/
netbe_rx_disable(sc->vsc_be);
/* Set sc->resetting and give a chance to the TX thread to stop. */
pthread_mutex_lock(&sc->tx_mtx);
sc->resetting = 1;
@ -158,9 +167,6 @@ pci_vtnet_reset(void *vsc)
pthread_mutex_lock(&sc->tx_mtx);
}
sc->rx_merge = 1;
sc->rx_vhdrlen = sizeof(struct virtio_net_rxhdr);
/*
* Now reset rings, MSI-X vectors, and negotiated capabilities.
* Do that with the TX lock held, since we need to reset
@ -512,8 +518,7 @@ pci_vtnet_init(struct vmctx *ctx, struct pci_devinst *pi, char *opts)
sc->resetting = 0;
sc->rx_merge = 1;
sc->rx_vhdrlen = sizeof(struct virtio_net_rxhdr);
sc->rx_merge = 0;
pthread_mutex_init(&sc->rx_mtx, NULL);
/*
@ -568,18 +573,24 @@ static void
pci_vtnet_neg_features(void *vsc, uint64_t negotiated_features)
{
struct pci_vtnet_softc *sc = vsc;
unsigned int rx_vhdrlen;
sc->vsc_features = negotiated_features;
if (!(negotiated_features & VIRTIO_NET_F_MRG_RXBUF)) {
if (negotiated_features & VIRTIO_NET_F_MRG_RXBUF) {
rx_vhdrlen = sizeof(struct virtio_net_rxhdr);
sc->rx_merge = 1;
} else {
/*
* Without mergeable rx buffers, virtio-net header is 2
* bytes shorter than sizeof(struct virtio_net_rxhdr).
*/
rx_vhdrlen = sizeof(struct virtio_net_rxhdr) - 2;
sc->rx_merge = 0;
/* Without mergeable rx buffers, virtio-net header is 2
* bytes shorter than sizeof(struct virtio_net_rxhdr). */
sc->rx_vhdrlen = sizeof(struct virtio_net_rxhdr) - 2;
}
/* Tell the backend to enable some capabilities it has advertised. */
netbe_set_cap(sc->vsc_be, negotiated_features, sc->rx_vhdrlen);
netbe_set_cap(sc->vsc_be, negotiated_features, rx_vhdrlen);
}
static struct pci_devemu pci_de_vnet = {