search for: virtqueue_desc_id_init

...+ * sgs. + * + * @page_xb_start and @page_xb_end form the range of bits in the xbitmap that + * need to be serached. + */ +static void tell_host_sgs(struct virtio_balloon *vb, + struct virtqueue *vq, + unsigned long page_xb_start, + unsigned long page_xb_end) +{ + unsigned int head_id = VIRTQUEUE_DESC_ID_INIT, + prev_id = VIRTQUEUE_DESC_ID_INIT; + unsigned long sg_pfn_start, sg_pfn_end; + uint64_t sg_addr; + uint32_t sg_size; + + sg_pfn_start = page_xb_start; + while (sg_pfn_start < page_xb_end) { + sg_pfn_start = xb_find_next_bit(&vb->page_xb, sg_pfn_start, + page_xb_end, 1); + i...

...+492,214 @@ static void update_balloon_size_func(struct work_struct *work) > queue_work(system_freezable_wq, work); > } > > +static unsigned int cmdq_hdr_add(struct virtqueue *vq, > + struct virtio_balloon_cmdq_hdr *hdr, > + bool in) > +{ > + unsigned int id = VIRTQUEUE_DESC_ID_INIT; > + uint64_t hdr_pa = (uint64_t)virt_to_phys((void *)hdr); > + > + virtqueue_add_chain_desc(vq, hdr_pa, sizeof(*hdr), &id, &id, in); > + > + /* Deliver the hdr for the host to send commands. */ > + if (in) { > + hdr->flags = 0; > + virtqueue_add_chain(vq, id, 0...

...+492,214 @@ static void update_balloon_size_func(struct work_struct *work) > queue_work(system_freezable_wq, work); > } > > +static unsigned int cmdq_hdr_add(struct virtqueue *vq, > + struct virtio_balloon_cmdq_hdr *hdr, > + bool in) > +{ > + unsigned int id = VIRTQUEUE_DESC_ID_INIT; > + uint64_t hdr_pa = (uint64_t)virt_to_phys((void *)hdr); > + > + virtqueue_add_chain_desc(vq, hdr_pa, sizeof(*hdr), &id, &id, in); > + > + /* Deliver the hdr for the host to send commands. */ > + if (in) { > + hdr->flags = 0; > + virtqueue_add_chain(vq, id, 0...

...struct notifier_block nb; }; @@ -485,25 +492,214 @@ static void update_balloon_size_func(struct work_struct *work) queue_work(system_freezable_wq, work); } +static unsigned int cmdq_hdr_add(struct virtqueue *vq, + struct virtio_balloon_cmdq_hdr *hdr, + bool in) +{ + unsigned int id = VIRTQUEUE_DESC_ID_INIT; + uint64_t hdr_pa = (uint64_t)virt_to_phys((void *)hdr); + + virtqueue_add_chain_desc(vq, hdr_pa, sizeof(*hdr), &id, &id, in); + + /* Deliver the hdr for the host to send commands. */ + if (in) { + hdr->flags = 0; + virtqueue_add_chain(vq, id, 0, NULL, hdr, NULL); + virtqueue_kick(vq...

This patch series enhances the existing virtio-balloon with the following new features: 1) fast ballooning: transfer ballooned pages between the guest and host in chunks using sgs, instead of one by one; and 2) cmdq: a new virtqueue to send commands between the device and driver. Currently, it supports commands to report memory stats (replace the old statq mechanism) and report guest unused pages.

This patch series enhances the existing virtio-balloon with the following new features: 1) fast ballooning: transfer ballooned pages between the guest and host in chunks using sgs, instead of one by one; and 2) cmdq: a new virtqueue to send commands between the device and driver. Currently, it supports commands to report memory stats (replace the old statq mechanism) and report guest unused pages.

...28b0e96..9f27101 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -57,8 +57,28 @@ int virtqueue_add_sgs(struct virtqueue *vq, > void *data, > gfp_t gfp); > > +/* A desc with this init id is treated as an invalid desc */ > +#define VIRTQUEUE_DESC_ID_INIT UINT_MAX > +int virtqueue_add_chain_desc(struct virtqueue *_vq, > + uint64_t addr, > + uint32_t len, > + unsigned int *head_id, > + unsigned int *prev_id, > + bool in); > + > +int virtqueue_add_chain(struct virtqueue *_vq, > + unsigned...

...28b0e96..9f27101 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -57,8 +57,28 @@ int virtqueue_add_sgs(struct virtqueue *vq, > void *data, > gfp_t gfp); > > +/* A desc with this init id is treated as an invalid desc */ > +#define VIRTQUEUE_DESC_ID_INIT UINT_MAX > +int virtqueue_add_chain_desc(struct virtqueue *_vq, > + uint64_t addr, > + uint32_t len, > + unsigned int *head_id, > + unsigned int *prev_id, > + bool in); > + > +int virtqueue_add_chain(struct virtqueue *_vq, > + unsigned...

....h > > > +++ b/include/linux/virtio.h > > > @@ -57,8 +57,28 @@ int virtqueue_add_sgs(struct virtqueue *vq, > > > void *data, > > > gfp_t gfp); > > > +/* A desc with this init id is treated as an invalid desc */ > > > +#define VIRTQUEUE_DESC_ID_INIT UINT_MAX > > > +int virtqueue_add_chain_desc(struct virtqueue *_vq, > > > + uint64_t addr, > > > + uint32_t len, > > > + unsigned int *head_id, > > > + unsigned int *prev_id, > > > + bool in); > > > +...

....h > > > +++ b/include/linux/virtio.h > > > @@ -57,8 +57,28 @@ int virtqueue_add_sgs(struct virtqueue *vq, > > > void *data, > > > gfp_t gfp); > > > +/* A desc with this init id is treated as an invalid desc */ > > > +#define VIRTQUEUE_DESC_ID_INIT UINT_MAX > > > +int virtqueue_add_chain_desc(struct virtqueue *_vq, > > > + uint64_t addr, > > > + uint32_t len, > > > + unsigned int *head_id, > > > + unsigned int *prev_id, > > > + bool in); > > > +...

...loon_size_func(struct work_struct *work) >> queue_work(system_freezable_wq, work); >> } >> >> +static unsigned int cmdq_hdr_add(struct virtqueue *vq, >> + struct virtio_balloon_cmdq_hdr *hdr, >> + bool in) >> +{ >> + unsigned int id = VIRTQUEUE_DESC_ID_INIT; >> + uint64_t hdr_pa = (uint64_t)virt_to_phys((void *)hdr); >> + >> + virtqueue_add_chain_desc(vq, hdr_pa, sizeof(*hdr), &id, &id, in); >> + >> + /* Deliver the hdr for the host to send commands. */ >> + if (in) { >> + hdr->flags = 0; >>...

...- a/include/linux/virtio.h >> +++ b/include/linux/virtio.h >> @@ -57,8 +57,28 @@ int virtqueue_add_sgs(struct virtqueue *vq, >> void *data, >> gfp_t gfp); >> >> +/* A desc with this init id is treated as an invalid desc */ >> +#define VIRTQUEUE_DESC_ID_INIT UINT_MAX >> +int virtqueue_add_chain_desc(struct virtqueue *_vq, >> + uint64_t addr, >> + uint32_t len, >> + unsigned int *head_id, >> + unsigned int *prev_id, >> + bool in); >> + >> +int virtqueue_add_chain(struct v...

...when inserting a new desc to the chain, right? > > As for the use, it would be better to do > > if (!add_next(vq, ...)) { > add_last(vq, ...) > kick > wait > } "!add_next(vq, ...)" means that the vq is full? If so, what would add_last() do then? > Using VIRTQUEUE_DESC_ID_INIT seems to avoid a branch in the driver, but > in fact it merely puts the branch in the virtio code. > Actually it wasn't intended to improve performance. It is used to indicate the "init" state of the chain. So, when virtqueue_add_chain_desc(, head_id,..) finds head id=INIT, i...

...xt(vq, ...)) { > > add_last(vq, ...) > > kick > > wait > > } > > "!add_next(vq, ...)" means that the vq is full? No - it means there's only 1 entry left for the last descriptor. > If so, what would add_last() > do then? > > > Using VIRTQUEUE_DESC_ID_INIT seems to avoid a branch in the driver, but > > in fact it merely puts the branch in the virtio code. > > > > Actually it wasn't intended to improve performance. It is used to indicate > the "init" state > of the chain. So, when virtqueue_add_chain_desc(, head...

...xt(vq, ...)) { > > add_last(vq, ...) > > kick > > wait > > } > > "!add_next(vq, ...)" means that the vq is full? No - it means there's only 1 entry left for the last descriptor. > If so, what would add_last() > do then? > > > Using VIRTQUEUE_DESC_ID_INIT seems to avoid a branch in the driver, but > > in fact it merely puts the branch in the virtio code. > > > > Actually it wasn't intended to improve performance. It is used to indicate > the "init" state > of the chain. So, when virtqueue_add_chain_desc(, head...