qemu/hw/9pfs/xen-9p-backend.c
Jason Andryuk 92e667f6fd 9pfs/xen: Fix segfault on shutdown
xen_9pfs_free can't use gnttabdev since it is already closed and NULL-ed
out when free is called.  Do the teardown in _disconnect().  This
matches the setup done in _connect().

trace-events are also added for the XenDevOps functions.

Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Message-Id: <20230502143722.15613-1-jandryuk@gmail.com>
[C.S.: - Remove redundant return in xen_9pfs_free().
       - Add comment to trace-events. ]
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
2023-05-16 16:21:54 +02:00

525 lines
16 KiB
C

/*
* Xen 9p backend
*
* Copyright Aporeto 2017
*
* Authors:
* Stefano Stabellini <stefano@aporeto.com>
*
*/
/*
* Not so fast! You might want to read the 9p developer docs first:
* https://wiki.qemu.org/Documentation/9p
*/
#include "qemu/osdep.h"
#include "hw/9pfs/9p.h"
#include "hw/xen/xen-legacy-backend.h"
#include "hw/9pfs/xen-9pfs.h"
#include "qapi/error.h"
#include "qemu/config-file.h"
#include "qemu/main-loop.h"
#include "qemu/option.h"
#include "qemu/iov.h"
#include "fsdev/qemu-fsdev.h"
#include "trace.h"
#define VERSIONS "1"
#define MAX_RINGS 8
#define MAX_RING_ORDER 9
typedef struct Xen9pfsRing {
struct Xen9pfsDev *priv;
int ref;
xenevtchn_handle *evtchndev;
int evtchn;
int local_port;
int ring_order;
struct xen_9pfs_data_intf *intf;
unsigned char *data;
struct xen_9pfs_data ring;
struct iovec *sg;
QEMUBH *bh;
Coroutine *co;
/* local copies, so that we can read/write PDU data directly from
* the ring */
RING_IDX out_cons, out_size, in_cons;
bool inprogress;
} Xen9pfsRing;
typedef struct Xen9pfsDev {
struct XenLegacyDevice xendev; /* must be first */
V9fsState state;
char *path;
char *security_model;
char *tag;
char *id;
int num_rings;
Xen9pfsRing *rings;
MemReentrancyGuard mem_reentrancy_guard;
} Xen9pfsDev;
static void xen_9pfs_disconnect(struct XenLegacyDevice *xendev);
static void xen_9pfs_in_sg(Xen9pfsRing *ring,
struct iovec *in_sg,
int *num,
uint32_t idx,
uint32_t size)
{
RING_IDX cons, prod, masked_prod, masked_cons;
cons = ring->intf->in_cons;
prod = ring->intf->in_prod;
xen_rmb();
masked_prod = xen_9pfs_mask(prod, XEN_FLEX_RING_SIZE(ring->ring_order));
masked_cons = xen_9pfs_mask(cons, XEN_FLEX_RING_SIZE(ring->ring_order));
if (masked_prod < masked_cons) {
in_sg[0].iov_base = ring->ring.in + masked_prod;
in_sg[0].iov_len = masked_cons - masked_prod;
*num = 1;
} else {
in_sg[0].iov_base = ring->ring.in + masked_prod;
in_sg[0].iov_len = XEN_FLEX_RING_SIZE(ring->ring_order) - masked_prod;
in_sg[1].iov_base = ring->ring.in;
in_sg[1].iov_len = masked_cons;
*num = 2;
}
}
static void xen_9pfs_out_sg(Xen9pfsRing *ring,
struct iovec *out_sg,
int *num,
uint32_t idx)
{
RING_IDX cons, prod, masked_prod, masked_cons;
cons = ring->intf->out_cons;
prod = ring->intf->out_prod;
xen_rmb();
masked_prod = xen_9pfs_mask(prod, XEN_FLEX_RING_SIZE(ring->ring_order));
masked_cons = xen_9pfs_mask(cons, XEN_FLEX_RING_SIZE(ring->ring_order));
if (masked_cons < masked_prod) {
out_sg[0].iov_base = ring->ring.out + masked_cons;
out_sg[0].iov_len = ring->out_size;
*num = 1;
} else {
if (ring->out_size >
(XEN_FLEX_RING_SIZE(ring->ring_order) - masked_cons)) {
out_sg[0].iov_base = ring->ring.out + masked_cons;
out_sg[0].iov_len = XEN_FLEX_RING_SIZE(ring->ring_order) -
masked_cons;
out_sg[1].iov_base = ring->ring.out;
out_sg[1].iov_len = ring->out_size -
(XEN_FLEX_RING_SIZE(ring->ring_order) -
masked_cons);
*num = 2;
} else {
out_sg[0].iov_base = ring->ring.out + masked_cons;
out_sg[0].iov_len = ring->out_size;
*num = 1;
}
}
}
static ssize_t xen_9pfs_pdu_vmarshal(V9fsPDU *pdu,
size_t offset,
const char *fmt,
va_list ap)
{
Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
struct iovec in_sg[2];
int num;
ssize_t ret;
xen_9pfs_in_sg(&xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings],
in_sg, &num, pdu->idx, ROUND_UP(offset + 128, 512));
ret = v9fs_iov_vmarshal(in_sg, num, offset, 0, fmt, ap);
if (ret < 0) {
xen_pv_printf(&xen_9pfs->xendev, 0,
"Failed to encode VirtFS reply type %d\n",
pdu->id + 1);
xen_be_set_state(&xen_9pfs->xendev, XenbusStateClosing);
xen_9pfs_disconnect(&xen_9pfs->xendev);
}
return ret;
}
static ssize_t xen_9pfs_pdu_vunmarshal(V9fsPDU *pdu,
size_t offset,
const char *fmt,
va_list ap)
{
Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
struct iovec out_sg[2];
int num;
ssize_t ret;
xen_9pfs_out_sg(&xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings],
out_sg, &num, pdu->idx);
ret = v9fs_iov_vunmarshal(out_sg, num, offset, 0, fmt, ap);
if (ret < 0) {
xen_pv_printf(&xen_9pfs->xendev, 0,
"Failed to decode VirtFS request type %d\n", pdu->id);
xen_be_set_state(&xen_9pfs->xendev, XenbusStateClosing);
xen_9pfs_disconnect(&xen_9pfs->xendev);
}
return ret;
}
static void xen_9pfs_init_out_iov_from_pdu(V9fsPDU *pdu,
struct iovec **piov,
unsigned int *pniov,
size_t size)
{
Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
Xen9pfsRing *ring = &xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings];
int num;
g_free(ring->sg);
ring->sg = g_new0(struct iovec, 2);
xen_9pfs_out_sg(ring, ring->sg, &num, pdu->idx);
*piov = ring->sg;
*pniov = num;
}
static void xen_9pfs_init_in_iov_from_pdu(V9fsPDU *pdu,
struct iovec **piov,
unsigned int *pniov,
size_t size)
{
Xen9pfsDev *xen_9pfs = container_of(pdu->s, Xen9pfsDev, state);
Xen9pfsRing *ring = &xen_9pfs->rings[pdu->tag % xen_9pfs->num_rings];
int num;
size_t buf_size;
g_free(ring->sg);
ring->sg = g_new0(struct iovec, 2);
ring->co = qemu_coroutine_self();
/* make sure other threads see ring->co changes before continuing */
smp_wmb();
again:
xen_9pfs_in_sg(ring, ring->sg, &num, pdu->idx, size);
buf_size = iov_size(ring->sg, num);
if (buf_size < size) {
qemu_coroutine_yield();
goto again;
}
ring->co = NULL;
/* make sure other threads see ring->co changes before continuing */
smp_wmb();
*piov = ring->sg;
*pniov = num;
}
static void xen_9pfs_push_and_notify(V9fsPDU *pdu)
{
RING_IDX prod;
Xen9pfsDev *priv = container_of(pdu->s, Xen9pfsDev, state);
Xen9pfsRing *ring = &priv->rings[pdu->tag % priv->num_rings];
g_free(ring->sg);
ring->sg = NULL;
ring->intf->out_cons = ring->out_cons;
xen_wmb();
prod = ring->intf->in_prod;
xen_rmb();
ring->intf->in_prod = prod + pdu->size;
xen_wmb();
ring->inprogress = false;
qemu_xen_evtchn_notify(ring->evtchndev, ring->local_port);
qemu_bh_schedule(ring->bh);
}
static const V9fsTransport xen_9p_transport = {
.pdu_vmarshal = xen_9pfs_pdu_vmarshal,
.pdu_vunmarshal = xen_9pfs_pdu_vunmarshal,
.init_in_iov_from_pdu = xen_9pfs_init_in_iov_from_pdu,
.init_out_iov_from_pdu = xen_9pfs_init_out_iov_from_pdu,
.push_and_notify = xen_9pfs_push_and_notify,
};
static int xen_9pfs_init(struct XenLegacyDevice *xendev)
{
return 0;
}
static int xen_9pfs_receive(Xen9pfsRing *ring)
{
P9MsgHeader h;
RING_IDX cons, prod, masked_prod, masked_cons, queued;
V9fsPDU *pdu;
if (ring->inprogress) {
return 0;
}
cons = ring->intf->out_cons;
prod = ring->intf->out_prod;
xen_rmb();
queued = xen_9pfs_queued(prod, cons, XEN_FLEX_RING_SIZE(ring->ring_order));
if (queued < sizeof(h)) {
return 0;
}
ring->inprogress = true;
masked_prod = xen_9pfs_mask(prod, XEN_FLEX_RING_SIZE(ring->ring_order));
masked_cons = xen_9pfs_mask(cons, XEN_FLEX_RING_SIZE(ring->ring_order));
xen_9pfs_read_packet((uint8_t *) &h, ring->ring.out, sizeof(h),
masked_prod, &masked_cons,
XEN_FLEX_RING_SIZE(ring->ring_order));
if (queued < le32_to_cpu(h.size_le)) {
return 0;
}
/* cannot fail, because we only handle one request per ring at a time */
pdu = pdu_alloc(&ring->priv->state);
ring->out_size = le32_to_cpu(h.size_le);
ring->out_cons = cons + le32_to_cpu(h.size_le);
pdu_submit(pdu, &h);
return 0;
}
static void xen_9pfs_bh(void *opaque)
{
Xen9pfsRing *ring = opaque;
bool wait;
again:
wait = ring->co != NULL && qemu_coroutine_entered(ring->co);
/* paired with the smb_wmb barriers in xen_9pfs_init_in_iov_from_pdu */
smp_rmb();
if (wait) {
cpu_relax();
goto again;
}
if (ring->co != NULL) {
qemu_coroutine_enter_if_inactive(ring->co);
}
xen_9pfs_receive(ring);
}
static void xen_9pfs_evtchn_event(void *opaque)
{
Xen9pfsRing *ring = opaque;
evtchn_port_t port;
port = qemu_xen_evtchn_pending(ring->evtchndev);
qemu_xen_evtchn_unmask(ring->evtchndev, port);
qemu_bh_schedule(ring->bh);
}
static void xen_9pfs_disconnect(struct XenLegacyDevice *xendev)
{
Xen9pfsDev *xen_9pdev = container_of(xendev, Xen9pfsDev, xendev);
int i;
trace_xen_9pfs_disconnect(xendev->name);
for (i = 0; i < xen_9pdev->num_rings; i++) {
if (xen_9pdev->rings[i].evtchndev != NULL) {
qemu_set_fd_handler(qemu_xen_evtchn_fd(xen_9pdev->rings[i].evtchndev),
NULL, NULL, NULL);
qemu_xen_evtchn_unbind(xen_9pdev->rings[i].evtchndev,
xen_9pdev->rings[i].local_port);
xen_9pdev->rings[i].evtchndev = NULL;
}
if (xen_9pdev->rings[i].data != NULL) {
xen_be_unmap_grant_refs(&xen_9pdev->xendev,
xen_9pdev->rings[i].data,
xen_9pdev->rings[i].intf->ref,
(1 << xen_9pdev->rings[i].ring_order));
xen_9pdev->rings[i].data = NULL;
}
if (xen_9pdev->rings[i].intf != NULL) {
xen_be_unmap_grant_ref(&xen_9pdev->xendev,
xen_9pdev->rings[i].intf,
xen_9pdev->rings[i].ref);
xen_9pdev->rings[i].intf = NULL;
}
if (xen_9pdev->rings[i].bh != NULL) {
qemu_bh_delete(xen_9pdev->rings[i].bh);
xen_9pdev->rings[i].bh = NULL;
}
}
g_free(xen_9pdev->id);
xen_9pdev->id = NULL;
g_free(xen_9pdev->tag);
xen_9pdev->tag = NULL;
g_free(xen_9pdev->path);
xen_9pdev->path = NULL;
g_free(xen_9pdev->security_model);
xen_9pdev->security_model = NULL;
g_free(xen_9pdev->rings);
xen_9pdev->rings = NULL;
}
static int xen_9pfs_free(struct XenLegacyDevice *xendev)
{
trace_xen_9pfs_free(xendev->name);
return 0;
}
static int xen_9pfs_connect(struct XenLegacyDevice *xendev)
{
Error *err = NULL;
int i;
Xen9pfsDev *xen_9pdev = container_of(xendev, Xen9pfsDev, xendev);
V9fsState *s = &xen_9pdev->state;
QemuOpts *fsdev;
trace_xen_9pfs_connect(xendev->name);
if (xenstore_read_fe_int(&xen_9pdev->xendev, "num-rings",
&xen_9pdev->num_rings) == -1 ||
xen_9pdev->num_rings > MAX_RINGS || xen_9pdev->num_rings < 1) {
return -1;
}
xen_9pdev->rings = g_new0(Xen9pfsRing, xen_9pdev->num_rings);
for (i = 0; i < xen_9pdev->num_rings; i++) {
char *str;
int ring_order;
xen_9pdev->rings[i].priv = xen_9pdev;
xen_9pdev->rings[i].evtchn = -1;
xen_9pdev->rings[i].local_port = -1;
str = g_strdup_printf("ring-ref%u", i);
if (xenstore_read_fe_int(&xen_9pdev->xendev, str,
&xen_9pdev->rings[i].ref) == -1) {
g_free(str);
goto out;
}
g_free(str);
str = g_strdup_printf("event-channel-%u", i);
if (xenstore_read_fe_int(&xen_9pdev->xendev, str,
&xen_9pdev->rings[i].evtchn) == -1) {
g_free(str);
goto out;
}
g_free(str);
xen_9pdev->rings[i].intf =
xen_be_map_grant_ref(&xen_9pdev->xendev,
xen_9pdev->rings[i].ref,
PROT_READ | PROT_WRITE);
if (!xen_9pdev->rings[i].intf) {
goto out;
}
ring_order = xen_9pdev->rings[i].intf->ring_order;
if (ring_order > MAX_RING_ORDER) {
goto out;
}
xen_9pdev->rings[i].ring_order = ring_order;
xen_9pdev->rings[i].data =
xen_be_map_grant_refs(&xen_9pdev->xendev,
xen_9pdev->rings[i].intf->ref,
(1 << ring_order),
PROT_READ | PROT_WRITE);
if (!xen_9pdev->rings[i].data) {
goto out;
}
xen_9pdev->rings[i].ring.in = xen_9pdev->rings[i].data;
xen_9pdev->rings[i].ring.out = xen_9pdev->rings[i].data +
XEN_FLEX_RING_SIZE(ring_order);
xen_9pdev->rings[i].bh = qemu_bh_new_guarded(xen_9pfs_bh,
&xen_9pdev->rings[i],
&xen_9pdev->mem_reentrancy_guard);
xen_9pdev->rings[i].out_cons = 0;
xen_9pdev->rings[i].out_size = 0;
xen_9pdev->rings[i].inprogress = false;
xen_9pdev->rings[i].evtchndev = qemu_xen_evtchn_open();
if (xen_9pdev->rings[i].evtchndev == NULL) {
goto out;
}
qemu_set_cloexec(qemu_xen_evtchn_fd(xen_9pdev->rings[i].evtchndev));
xen_9pdev->rings[i].local_port = qemu_xen_evtchn_bind_interdomain
(xen_9pdev->rings[i].evtchndev,
xendev->dom,
xen_9pdev->rings[i].evtchn);
if (xen_9pdev->rings[i].local_port == -1) {
xen_pv_printf(xendev, 0,
"xenevtchn_bind_interdomain failed port=%d\n",
xen_9pdev->rings[i].evtchn);
goto out;
}
xen_pv_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
qemu_set_fd_handler(qemu_xen_evtchn_fd(xen_9pdev->rings[i].evtchndev),
xen_9pfs_evtchn_event, NULL, &xen_9pdev->rings[i]);
}
xen_9pdev->security_model = xenstore_read_be_str(xendev, "security_model");
xen_9pdev->path = xenstore_read_be_str(xendev, "path");
xen_9pdev->id = s->fsconf.fsdev_id =
g_strdup_printf("xen9p%d", xendev->dev);
xen_9pdev->tag = s->fsconf.tag = xenstore_read_fe_str(xendev, "tag");
fsdev = qemu_opts_create(qemu_find_opts("fsdev"),
s->fsconf.tag,
1, NULL);
qemu_opt_set(fsdev, "fsdriver", "local", NULL);
qemu_opt_set(fsdev, "path", xen_9pdev->path, NULL);
qemu_opt_set(fsdev, "security_model", xen_9pdev->security_model, NULL);
qemu_opts_set_id(fsdev, s->fsconf.fsdev_id);
qemu_fsdev_add(fsdev, &err);
if (err) {
error_report_err(err);
}
v9fs_device_realize_common(s, &xen_9p_transport, NULL);
return 0;
out:
xen_9pfs_free(xendev);
return -1;
}
static void xen_9pfs_alloc(struct XenLegacyDevice *xendev)
{
trace_xen_9pfs_alloc(xendev->name);
xenstore_write_be_str(xendev, "versions", VERSIONS);
xenstore_write_be_int(xendev, "max-rings", MAX_RINGS);
xenstore_write_be_int(xendev, "max-ring-page-order", MAX_RING_ORDER);
}
struct XenDevOps xen_9pfs_ops = {
.size = sizeof(Xen9pfsDev),
.flags = DEVOPS_FLAG_NEED_GNTDEV,
.alloc = xen_9pfs_alloc,
.init = xen_9pfs_init,
.initialise = xen_9pfs_connect,
.disconnect = xen_9pfs_disconnect,
.free = xen_9pfs_free,
};