From b0e5d90ebc3edb5cfc1d5d33dd3334482dee6d46 Mon Sep 17 00:00:00 2001 From: Cornelia Huck Date: Mon, 26 Jan 2015 17:26:42 +0100 Subject: [PATCH] dataplane: endianness-aware accesses The vring.c code currently assumes that guest and host endianness match, which is not true for a number of cases: - emulating targets with a different endianness than the host - bi-endian targets, where the correct endianness depends on the virtio device - upcoming support for the virtio-1 standard mandates little-endian accesses even for big-endian targets and hosts Make sure to use accessors that depend on the virtio device. Note that dataplane now needs to be built per-target. Cc: Stefan Hajnoczi Cc: Paolo Bonzini Cc: Fam Zheng Reviewed-by: David Gibson Tested-by: David Gibson Signed-off-by: Cornelia Huck Reviewed-by: Stefan Hajnoczi Message-id: 1422289602-17874-2-git-send-email-cornelia.huck@de.ibm.com Signed-off-by: Stefan Hajnoczi --- hw/block/dataplane/virtio-blk.c | 4 +- hw/scsi/virtio-scsi-dataplane.c | 2 +- hw/virtio/Makefile.objs | 2 +- hw/virtio/dataplane/Makefile.objs | 2 +- hw/virtio/dataplane/vring.c | 53 ++++++++----- include/hw/virtio/dataplane/vring-accessors.h | 75 +++++++++++++++++++ include/hw/virtio/dataplane/vring.h | 14 +--- 7 files changed, 117 insertions(+), 35 deletions(-) create mode 100644 include/hw/virtio/dataplane/vring-accessors.h diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index be957d1117..cd41478b08 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -16,7 +16,9 @@ #include "qemu/iov.h" #include "qemu/thread.h" #include "qemu/error-report.h" +#include "hw/virtio/virtio-access.h" #include "hw/virtio/dataplane/vring.h" +#include "hw/virtio/dataplane/vring-accessors.h" #include "sysemu/block-backend.h" #include "hw/virtio/virtio-blk.h" #include "virtio-blk.h" @@ -75,7 +77,7 @@ static void complete_request_vring(VirtIOBlockReq *req, unsigned char status) VirtIOBlockDataPlane *s = req->dev->dataplane; stb_p(&req->in->status, status); - vring_push(&req->dev->dataplane->vring, &req->elem, + vring_push(s->vdev, &req->dev->dataplane->vring, &req->elem, req->qiov.size + sizeof(*req->in)); /* Suppress notification to guest by BH and its scheduled diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c index 03a1e8cfcf..418d73b1b4 100644 --- a/hw/scsi/virtio-scsi-dataplane.c +++ b/hw/scsi/virtio-scsi-dataplane.c @@ -94,7 +94,7 @@ void virtio_scsi_vring_push_notify(VirtIOSCSIReq *req) { VirtIODevice *vdev = VIRTIO_DEVICE(req->vring->parent); - vring_push(&req->vring->vring, &req->elem, + vring_push(vdev, &req->vring->vring, &req->elem, req->qsgl.size + req->resp_iov.size); if (vring_should_notify(vdev, &req->vring->vring)) { diff --git a/hw/virtio/Makefile.objs b/hw/virtio/Makefile.objs index d21c397756..19b224a44d 100644 --- a/hw/virtio/Makefile.objs +++ b/hw/virtio/Makefile.objs @@ -2,7 +2,7 @@ common-obj-y += virtio-rng.o common-obj-$(CONFIG_VIRTIO_PCI) += virtio-pci.o common-obj-y += virtio-bus.o common-obj-y += virtio-mmio.o -common-obj-$(CONFIG_VIRTIO) += dataplane/ +obj-$(CONFIG_VIRTIO) += dataplane/ obj-y += virtio.o virtio-balloon.o obj-$(CONFIG_LINUX) += vhost.o vhost-backend.o vhost-user.o diff --git a/hw/virtio/dataplane/Makefile.objs b/hw/virtio/dataplane/Makefile.objs index 9a8cfc0297..753a9cab44 100644 --- a/hw/virtio/dataplane/Makefile.objs +++ b/hw/virtio/dataplane/Makefile.objs @@ -1 +1 @@ -common-obj-y += vring.o +obj-y += vring.o diff --git a/hw/virtio/dataplane/vring.c b/hw/virtio/dataplane/vring.c index 78c6f45a07..0936f659e5 100644 --- a/hw/virtio/dataplane/vring.c +++ b/hw/virtio/dataplane/vring.c @@ -18,7 +18,9 @@ #include "hw/hw.h" #include "exec/memory.h" #include "exec/address-spaces.h" +#include "hw/virtio/virtio-access.h" #include "hw/virtio/dataplane/vring.h" +#include "hw/virtio/dataplane/vring-accessors.h" #include "qemu/error-report.h" /* vring_map can be coupled with vring_unmap or (if you still have the @@ -83,7 +85,7 @@ bool vring_setup(Vring *vring, VirtIODevice *vdev, int n) vring_init(&vring->vr, virtio_queue_get_num(vdev, n), vring_ptr, 4096); vring->last_avail_idx = virtio_queue_get_last_avail_idx(vdev, n); - vring->last_used_idx = vring->vr.used->idx; + vring->last_used_idx = vring_get_used_idx(vdev, vring); vring->signalled_used = 0; vring->signalled_used_valid = false; @@ -104,7 +106,7 @@ void vring_teardown(Vring *vring, VirtIODevice *vdev, int n) void vring_disable_notification(VirtIODevice *vdev, Vring *vring) { if (!(vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX))) { - vring->vr.used->flags |= VRING_USED_F_NO_NOTIFY; + vring_set_used_flags(vdev, vring, VRING_USED_F_NO_NOTIFY); } } @@ -117,10 +119,10 @@ bool vring_enable_notification(VirtIODevice *vdev, Vring *vring) if (vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX)) { vring_avail_event(&vring->vr) = vring->vr.avail->idx; } else { - vring->vr.used->flags &= ~VRING_USED_F_NO_NOTIFY; + vring_clear_used_flags(vdev, vring, VRING_USED_F_NO_NOTIFY); } smp_mb(); /* ensure update is seen before reading avail_idx */ - return !vring_more_avail(vring); + return !vring_more_avail(vdev, vring); } /* This is stolen from linux/drivers/vhost/vhost.c:vhost_notify() */ @@ -134,12 +136,13 @@ bool vring_should_notify(VirtIODevice *vdev, Vring *vring) smp_mb(); if ((vdev->guest_features & (1 << VIRTIO_F_NOTIFY_ON_EMPTY)) && - unlikely(vring->vr.avail->idx == vring->last_avail_idx)) { + unlikely(!vring_more_avail(vdev, vring))) { return true; } if (!(vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX))) { - return !(vring->vr.avail->flags & VRING_AVAIL_F_NO_INTERRUPT); + return !(vring_get_avail_flags(vdev, vring) & + VRING_AVAIL_F_NO_INTERRUPT); } old = vring->signalled_used; v = vring->signalled_used_valid; @@ -202,9 +205,19 @@ static int get_desc(Vring *vring, VirtQueueElement *elem, return 0; } +static void copy_in_vring_desc(VirtIODevice *vdev, + const struct vring_desc *guest, + struct vring_desc *host) +{ + host->addr = virtio_ldq_p(vdev, &guest->addr); + host->len = virtio_ldl_p(vdev, &guest->len); + host->flags = virtio_lduw_p(vdev, &guest->flags); + host->next = virtio_lduw_p(vdev, &guest->next); +} + /* This is stolen from linux/drivers/vhost/vhost.c. */ -static int get_indirect(Vring *vring, VirtQueueElement *elem, - struct vring_desc *indirect) +static int get_indirect(VirtIODevice *vdev, Vring *vring, + VirtQueueElement *elem, struct vring_desc *indirect) { struct vring_desc desc; unsigned int i = 0, count, found = 0; @@ -244,7 +257,7 @@ static int get_indirect(Vring *vring, VirtQueueElement *elem, vring->broken = true; return -EFAULT; } - desc = *desc_ptr; + copy_in_vring_desc(vdev, desc_ptr, &desc); memory_region_unref(mr); /* Ensure descriptor has been loaded before accessing fields */ @@ -320,7 +333,7 @@ int vring_pop(VirtIODevice *vdev, Vring *vring, /* Check it isn't doing very strange things with descriptor numbers. */ last_avail_idx = vring->last_avail_idx; - avail_idx = vring->vr.avail->idx; + avail_idx = vring_get_avail_idx(vdev, vring); barrier(); /* load indices now and not again later */ if (unlikely((uint16_t)(avail_idx - last_avail_idx) > num)) { @@ -341,7 +354,7 @@ int vring_pop(VirtIODevice *vdev, Vring *vring, /* Grab the next descriptor number they're advertising, and increment * the index we've seen. */ - head = vring->vr.avail->ring[last_avail_idx % num]; + head = vring_get_avail_ring(vdev, vring, last_avail_idx % num); elem->index = head; @@ -365,13 +378,13 @@ int vring_pop(VirtIODevice *vdev, Vring *vring, ret = -EFAULT; goto out; } - desc = vring->vr.desc[i]; + copy_in_vring_desc(vdev, &vring->vr.desc[i], &desc); /* Ensure descriptor is loaded before accessing fields */ barrier(); if (desc.flags & VRING_DESC_F_INDIRECT) { - ret = get_indirect(vring, elem, &desc); + ret = get_indirect(vdev, vring, elem, &desc); if (ret < 0) { goto out; } @@ -407,9 +420,9 @@ out: * * Stolen from linux/drivers/vhost/vhost.c. */ -void vring_push(Vring *vring, VirtQueueElement *elem, int len) +void vring_push(VirtIODevice *vdev, Vring *vring, VirtQueueElement *elem, + int len) { - struct vring_used_elem *used; unsigned int head = elem->index; uint16_t new; @@ -422,14 +435,16 @@ void vring_push(Vring *vring, VirtQueueElement *elem, int len) /* The virtqueue contains a ring of used buffers. Get a pointer to the * next entry in that used ring. */ - used = &vring->vr.used->ring[vring->last_used_idx % vring->vr.num]; - used->id = head; - used->len = len; + vring_set_used_ring_id(vdev, vring, vring->last_used_idx % vring->vr.num, + head); + vring_set_used_ring_len(vdev, vring, vring->last_used_idx % vring->vr.num, + len); /* Make sure buffer is written before we update index. */ smp_wmb(); - new = vring->vr.used->idx = ++vring->last_used_idx; + new = ++vring->last_used_idx; + vring_set_used_idx(vdev, vring, new); if (unlikely((int16_t)(new - vring->signalled_used) < (uint16_t)1)) { vring->signalled_used_valid = false; } diff --git a/include/hw/virtio/dataplane/vring-accessors.h b/include/hw/virtio/dataplane/vring-accessors.h new file mode 100644 index 0000000000..b508b87900 --- /dev/null +++ b/include/hw/virtio/dataplane/vring-accessors.h @@ -0,0 +1,75 @@ +#ifndef VRING_ACCESSORS_H +#define VRING_ACCESSORS_H + +#include "hw/virtio/virtio_ring.h" +#include "hw/virtio/virtio.h" +#include "hw/virtio/virtio-access.h" + +static inline uint16_t vring_get_used_idx(VirtIODevice *vdev, Vring *vring) +{ + return virtio_tswap16(vdev, vring->vr.used->idx); +} + +static inline void vring_set_used_idx(VirtIODevice *vdev, Vring *vring, + uint16_t idx) +{ + vring->vr.used->idx = virtio_tswap16(vdev, idx); +} + +static inline uint16_t vring_get_avail_idx(VirtIODevice *vdev, Vring *vring) +{ + return virtio_tswap16(vdev, vring->vr.avail->idx); +} + +static inline uint16_t vring_get_avail_ring(VirtIODevice *vdev, Vring *vring, + int i) +{ + return virtio_tswap16(vdev, vring->vr.avail->ring[i]); +} + +static inline void vring_set_used_ring_id(VirtIODevice *vdev, Vring *vring, + int i, uint32_t id) +{ + vring->vr.used->ring[i].id = virtio_tswap32(vdev, id); +} + +static inline void vring_set_used_ring_len(VirtIODevice *vdev, Vring *vring, + int i, uint32_t len) +{ + vring->vr.used->ring[i].len = virtio_tswap32(vdev, len); +} + +static inline uint16_t vring_get_used_flags(VirtIODevice *vdev, Vring *vring) +{ + return virtio_tswap16(vdev, vring->vr.used->flags); +} + +static inline uint16_t vring_get_avail_flags(VirtIODevice *vdev, Vring *vring) +{ + return virtio_tswap16(vdev, vring->vr.avail->flags); +} + +static inline void vring_set_used_flags(VirtIODevice *vdev, Vring *vring, + uint16_t flags) +{ + vring->vr.used->flags |= virtio_tswap16(vdev, flags); +} + +static inline void vring_clear_used_flags(VirtIODevice *vdev, Vring *vring, + uint16_t flags) +{ + vring->vr.used->flags &= virtio_tswap16(vdev, ~flags); +} + +static inline unsigned int vring_get_num(Vring *vring) +{ + return vring->vr.num; +} + +/* Are there more descriptors available? */ +static inline bool vring_more_avail(VirtIODevice *vdev, Vring *vring) +{ + return vring_get_avail_idx(vdev, vring) != vring->last_avail_idx; +} + +#endif diff --git a/include/hw/virtio/dataplane/vring.h b/include/hw/virtio/dataplane/vring.h index d3e086aefc..e42c0fc9cc 100644 --- a/include/hw/virtio/dataplane/vring.h +++ b/include/hw/virtio/dataplane/vring.h @@ -31,17 +31,6 @@ typedef struct { bool broken; /* was there a fatal error? */ } Vring; -static inline unsigned int vring_get_num(Vring *vring) -{ - return vring->vr.num; -} - -/* Are there more descriptors available? */ -static inline bool vring_more_avail(Vring *vring) -{ - return vring->vr.avail->idx != vring->last_avail_idx; -} - /* Fail future vring_pop() and vring_push() calls until reset */ static inline void vring_set_broken(Vring *vring) { @@ -54,6 +43,7 @@ void vring_disable_notification(VirtIODevice *vdev, Vring *vring); bool vring_enable_notification(VirtIODevice *vdev, Vring *vring); bool vring_should_notify(VirtIODevice *vdev, Vring *vring); int vring_pop(VirtIODevice *vdev, Vring *vring, VirtQueueElement *elem); -void vring_push(Vring *vring, VirtQueueElement *elem, int len); +void vring_push(VirtIODevice *vdev, Vring *vring, VirtQueueElement *elem, + int len); #endif /* VRING_H */