storvsc currently sets .dma_boundary to limit scatterlist entries to 4 Kbytes, which is less efficient with huge pages that offer large chunks of contiguous physical memory. Improve the algorithm for creating the Hyper-V guest physical address PFN array so that scatterlist entries with lengths > 4Kbytes are handled. As a result, remove the .dma_boundary setting.
The improved algorithm also adds support for scatterlist entries with offsets >= 4Kbytes, which is supported by many other SCSI low-level drivers. And it retains support for architectures where possibly PAGE_SIZE != HV_HYP_PAGE_SIZE (such as ARM64). Signed-off-by: Michael Kelley <mikel...@microsoft.com> --- Changes in v2: * Add HVPFN_DOWN() macro and use it instead of open coding [Vitaly Kuznetsov] * Change loop that fills pfn array and its initialization [Vitaly Kuznetsov] * Use offset_in_hvpage() instead of open coding drivers/scsi/storvsc_drv.c | 66 ++++++++++++++++------------------------------ include/linux/hyperv.h | 1 + 2 files changed, 24 insertions(+), 43 deletions(-) diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c index 2e4fa77..5ba3145 100644 --- a/drivers/scsi/storvsc_drv.c +++ b/drivers/scsi/storvsc_drv.c @@ -1678,9 +1678,8 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd) struct storvsc_cmd_request *cmd_request = scsi_cmd_priv(scmnd); int i; struct scatterlist *sgl; - unsigned int sg_count = 0; + unsigned int sg_count; struct vmscsi_request *vm_srb; - struct scatterlist *cur_sgl; struct vmbus_packet_mpb_array *payload; u32 payload_sz; u32 length; @@ -1759,8 +1758,8 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd) payload_sz = sizeof(cmd_request->mpb); if (sg_count) { - unsigned int hvpgoff = 0; - unsigned long offset_in_hvpg = sgl->offset & ~HV_HYP_PAGE_MASK; + unsigned int hvpgoff, hvpfns_to_add; + unsigned long offset_in_hvpg = offset_in_hvpage(sgl->offset); unsigned int hvpg_count = HVPFN_UP(offset_in_hvpg + length); u64 hvpfn; @@ -1773,51 +1772,34 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd) return SCSI_MLQUEUE_DEVICE_BUSY; } - /* - * sgl is a list of PAGEs, and payload->range.pfn_array - * expects the page number in the unit of HV_HYP_PAGE_SIZE (the - * page size that Hyper-V uses, so here we need to divide PAGEs - * into HV_HYP_PAGE in case that PAGE_SIZE > HV_HYP_PAGE_SIZE. - * Besides, payload->range.offset should be the offset in one - * HV_HYP_PAGE. - */ payload->range.len = length; payload->range.offset = offset_in_hvpg; - hvpgoff = sgl->offset >> HV_HYP_PAGE_SHIFT; - cur_sgl = sgl; - for (i = 0; i < hvpg_count; i++) { + + for (i = 0; sgl != NULL; sgl = sg_next(sgl)) { /* - * 'i' is the index of hv pages in the payload and - * 'hvpgoff' is the offset (in hv pages) of the first - * hv page in the the first page. The relationship - * between the sum of 'i' and 'hvpgoff' and the offset - * (in hv pages) in a payload page ('hvpgoff_in_page') - * is as follow: - * - * |------------------ PAGE -------------------| - * | NR_HV_HYP_PAGES_IN_PAGE hvpgs in total | - * |hvpg|hvpg| ... |hvpg|... |hvpg| - * ^ ^ ^ ^ - * +-hvpgoff-+ +-hvpgoff_in_page-+ - * ^ | - * +--------------------- i ---------------------------+ + * Init values for the current sgl entry. hvpgoff + * and hvpfns_to_add are in units of Hyper-V size + * pages. Handling the PAGE_SIZE != HV_HYP_PAGE_SIZE + * case also handles values of sgl->offset that are + * larger than PAGE_SIZE. Such offsets are handled + * even on other than the first sgl entry, provided + * they are a multiple of PAGE_SIZE. */ - unsigned int hvpgoff_in_page = - (i + hvpgoff) % NR_HV_HYP_PAGES_IN_PAGE; + hvpgoff = HVPFN_DOWN(sgl->offset); + hvpfn = page_to_hvpfn(sg_page(sgl)) + hvpgoff; + hvpfns_to_add = HVPFN_UP(sgl->offset + sgl->length) - + hvpgoff; /* - * Two cases that we need to fetch a page: - * 1) i == 0, the first step or - * 2) hvpgoff_in_page == 0, when we reach the boundary - * of a page. + * Fill the next portion of the PFN array with + * sequential Hyper-V PFNs for the continguous physical + * memory described by the sgl entry. The end of the + * last sgl should be reached at the same time that + * the PFN array is filled. */ - if (hvpgoff_in_page == 0 || i == 0) { - hvpfn = page_to_hvpfn(sg_page(cur_sgl)); - cur_sgl = sg_next(cur_sgl); - } - - payload->range.pfn_array[i] = hvpfn + hvpgoff_in_page; + while (hvpfns_to_add--) + payload->range.pfn_array[i++] = hvpfn++; } } @@ -1851,8 +1833,6 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd) .slave_configure = storvsc_device_configure, .cmd_per_lun = 2048, .this_id = -1, - /* Make sure we dont get a sg segment crosses a page boundary */ - .dma_boundary = PAGE_SIZE-1, /* Ensure there are no gaps in presented sgls */ .virt_boundary_mask = PAGE_SIZE-1, .no_write_same = 1, diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index 5ddb479..a1eed76 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -1717,6 +1717,7 @@ static inline unsigned long virt_to_hvpfn(void *addr) #define NR_HV_HYP_PAGES_IN_PAGE (PAGE_SIZE / HV_HYP_PAGE_SIZE) #define offset_in_hvpage(ptr) ((unsigned long)(ptr) & ~HV_HYP_PAGE_MASK) #define HVPFN_UP(x) (((x) + HV_HYP_PAGE_SIZE-1) >> HV_HYP_PAGE_SHIFT) +#define HVPFN_DOWN(x) ((x) >> HV_HYP_PAGE_SHIFT) #define page_to_hvpfn(page) (page_to_pfn(page) * NR_HV_HYP_PAGES_IN_PAGE) #endif /* _HYPERV_H */ -- 1.8.3.1