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Subject[RFC PATCH V4 11/12] HV/Storvsc: Add Isolation VM support for storvsc driver
Date
From: Tianyu Lan <Tianyu.Lan@microsoft.com>

In Isolation VM, all shared memory with host needs to mark visible
to host via hvcall. vmbus_establish_gpadl() has already done it for
storvsc rx/tx ring buffer. The page buffer used by vmbus_sendpacket_
mpb_desc() still need to handle. Use DMA API to map/umap these
memory during sending/receiving packet and Hyper-V DMA ops callback
will use swiotlb function to allocate bounce buffer and copy data
from/to bounce buffer.

Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
drivers/scsi/storvsc_drv.c | 68 +++++++++++++++++++++++++++++++++++---
1 file changed, 63 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 403753929320..cc9cb32f6621 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -21,6 +21,8 @@
#include <linux/device.h>
#include <linux/hyperv.h>
#include <linux/blkdev.h>
+#include <linux/io.h>
+#include <linux/dma-mapping.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_host.h>
@@ -427,6 +429,8 @@ struct storvsc_cmd_request {
u32 payload_sz;

struct vstor_packet vstor_packet;
+ u32 hvpg_count;
+ struct hv_dma_range *dma_range;
};


@@ -509,6 +513,14 @@ struct storvsc_scan_work {
u8 tgt_id;
};

+#define storvsc_dma_map(dev, page, offset, size, dir) \
+ dma_map_page(dev, page, offset, size, dir)
+
+#define storvsc_dma_unmap(dev, dma_range, dir) \
+ dma_unmap_page(dev, dma_range.dma, \
+ dma_range.mapping_size, \
+ dir ? DMA_FROM_DEVICE : DMA_TO_DEVICE)
+
static void storvsc_device_scan(struct work_struct *work)
{
struct storvsc_scan_work *wrk;
@@ -1267,6 +1279,7 @@ static void storvsc_on_channel_callback(void *context)
struct hv_device *device;
struct storvsc_device *stor_device;
struct Scsi_Host *shost;
+ int i;

if (channel->primary_channel != NULL)
device = channel->primary_channel->device_obj;
@@ -1321,6 +1334,15 @@ static void storvsc_on_channel_callback(void *context)
request = (struct storvsc_cmd_request *)scsi_cmd_priv(scmnd);
}

+ if (request->dma_range) {
+ for (i = 0; i < request->hvpg_count; i++)
+ storvsc_dma_unmap(&device->device,
+ request->dma_range[i],
+ request->vstor_packet.vm_srb.data_in == READ_TYPE);
+
+ kfree(request->dma_range);
+ }
+
storvsc_on_receive(stor_device, packet, request);
continue;
}
@@ -1817,7 +1839,9 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
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);
+ dma_addr_t dma;
u64 hvpfn;
+ u32 size;

if (hvpg_count > MAX_PAGE_BUFFER_COUNT) {

@@ -1831,6 +1855,13 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
payload->range.len = length;
payload->range.offset = offset_in_hvpg;

+ cmd_request->dma_range = kcalloc(hvpg_count,
+ sizeof(*cmd_request->dma_range),
+ GFP_ATOMIC);
+ if (!cmd_request->dma_range) {
+ ret = -ENOMEM;
+ goto free_payload;
+ }

for (i = 0; sgl != NULL; sgl = sg_next(sgl)) {
/*
@@ -1854,9 +1885,29 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
* last sgl should be reached at the same time that
* the PFN array is filled.
*/
- while (hvpfns_to_add--)
- payload->range.pfn_array[i++] = hvpfn++;
+ while (hvpfns_to_add--) {
+ size = min(HV_HYP_PAGE_SIZE - offset_in_hvpg,
+ (unsigned long)length);
+ dma = storvsc_dma_map(&dev->device, pfn_to_page(hvpfn++),
+ offset_in_hvpg, size,
+ scmnd->sc_data_direction);
+ if (dma_mapping_error(&dev->device, dma)) {
+ ret = -ENOMEM;
+ goto free_dma_range;
+ }
+
+ if (offset_in_hvpg) {
+ payload->range.offset = dma & ~HV_HYP_PAGE_MASK;
+ offset_in_hvpg = 0;
+ }
+
+ cmd_request->dma_range[i].dma = dma;
+ cmd_request->dma_range[i].mapping_size = size;
+ payload->range.pfn_array[i++] = dma >> HV_HYP_PAGE_SHIFT;
+ length -= size;
+ }
}
+ cmd_request->hvpg_count = hvpg_count;
}

cmd_request->payload = payload;
@@ -1867,13 +1918,20 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
put_cpu();

if (ret == -EAGAIN) {
- if (payload_sz > sizeof(cmd_request->mpb))
- kfree(payload);
/* no more space */
- return SCSI_MLQUEUE_DEVICE_BUSY;
+ ret = SCSI_MLQUEUE_DEVICE_BUSY;
+ goto free_dma_range;
}

return 0;
+
+free_dma_range:
+ kfree(cmd_request->dma_range);
+
+free_payload:
+ if (payload_sz > sizeof(cmd_request->mpb))
+ kfree(payload);
+ return ret;
}

static struct scsi_host_template scsi_driver = {
--
2.25.1
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