[v2,1/1] scsi: storvsc: Enable scatterlist entry lengths > 4Kbytes
diff mbox series

Message ID 1614120294-1930-1-git-send-email-mikelley@microsoft.com
State Accepted
Commit 3d9c3dcc58e968403f29767726407bc680e087b5
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Series
  • [v2,1/1] scsi: storvsc: Enable scatterlist entry lengths > 4Kbytes
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Commit Message

Michael Kelley Feb. 23, 2021, 10:44 p.m. UTC
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 <mikelley@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(-)

Comments

Vitaly Kuznetsov March 3, 2021, 9:08 a.m. UTC | #1
Michael Kelley <mikelley@microsoft.com> writes:

> 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 <mikelley@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 */

Thank you for implementing my suggestion in v2,

Reviewed-by:  Vitaly Kuznetsov <vkuznets@redhat.com>
Michael Kelley March 16, 2021, 3:29 p.m. UTC | #2
From: Vitaly Kuznetsov <vkuznets@redhat.com> Sent: Wednesday, March 3, 2021 1:09 AM
> To: Michael Kelley <mikelley@microsoft.com>
> Cc: KY Srinivasan <kys@microsoft.com>; martin.petersen@oracle.com; Long Li
> <longli@microsoft.com>; wei.liu@kernel.org; jejb@linux.ibm.com; linux-
> hyperv@vger.kernel.org; linux-kernel@vger.kernel.org; linux-scsi@vger.kernel.org
> Subject: Re: [PATCH v2 1/1] scsi: storvsc: Enable scatterlist entry lengths > 4Kbytes
> 
> Michael Kelley <mikelley@microsoft.com> writes:
> 
> > 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 <mikelley@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 */
> 
> Thank you for implementing my suggestion in v2,
> 
> Reviewed-by:  Vitaly Kuznetsov <vkuznets@redhat.com>
> 
> --
> Vitaly

Martin -- Is anything else needed for you to pick up this patch?

Michael
Martin K. Petersen March 19, 2021, 3:46 a.m. UTC | #3
On Tue, 23 Feb 2021 14:44:54 -0800, Michael Kelley wrote:

> 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.
> 
> [...]

Applied to 5.13/scsi-queue, thanks!

[1/1] scsi: storvsc: Enable scatterlist entry lengths > 4Kbytes
      https://git.kernel.org/mkp/scsi/c/3d9c3dcc58e9

Patch
diff mbox series

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 */