[PATCH v6 7/8] PCI/NTB: endpoint: Allow DMA and MW to share a BAR

[Koichiro Den <den@valinux.co.jp>]

Some endpoint configurations have no spare BAR for DMA resources. Allow
dma_bar to select an MW BAR and place the DMA ranges after that MW.

DMA submaps have fixed BAR offsets, so a shared MW translation must
cover its configured size. Report that size as the translation alignment
and require it to be a power of two.

Limit the host-visible MW size to exclude the DMA ranges. Older versions
of ntb_hw_epf treat the whole BAR as an MW.

Signed-off-by: Koichiro Den <den@valinux.co.jp>
---
Changes since v5:
  - Include the host-side MW boundary handling and place this patch
    after DMA discovery.

 drivers/ntb/hw/epf/ntb_hw_epf.c               |  43 ++++-
 drivers/pci/endpoint/functions/pci-epf-vntb.c | 147 +++++++++++++-----
 2 files changed, 148 insertions(+), 42 deletions(-)

diff --git a/drivers/ntb/hw/epf/ntb_hw_epf.c b/drivers/ntb/hw/epf/ntb_hw_epf.c
index e0016128b95c..975ea424de6a 100644
--- a/drivers/ntb/hw/epf/ntb_hw_epf.c
+++ b/drivers/ntb/hw/epf/ntb_hw_epf.c
@@ -382,6 +382,23 @@ static int ntb_epf_mw_to_bar(struct ntb_epf_dev *ndev, int idx)
 	return ndev->barno_map[BAR_MW1 + idx];
 }
 
+static resource_size_t ntb_epf_mw_offset(struct ntb_epf_dev *ndev, int idx)
+{
+	return !idx ? readl(ndev->ctrl_reg + NTB_EPF_CTRL(mw1_offset)) : 0;
+}
+
+static resource_size_t ntb_epf_mw_size(struct ntb_epf_dev *ndev, int bar)
+{
+	resource_size_t end;
+
+	end = pci_resource_len(ndev->ntb.pdev, bar);
+	/* The DMA submap offset marks the end of an MW sharing this BAR. */
+	if (ndev->dma.submap.size && ndev->dma.submap.bar == bar)
+		end = min(end, ndev->dma.submap.offset);
+
+	return end;
+}
+
 static int ntb_epf_mw_count(struct ntb_dev *ntb, int pidx)
 {
 	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
@@ -420,7 +437,7 @@ static int ntb_epf_mw_get_align(struct ntb_dev *ntb, int pidx, int idx,
 		*size_align = 1;
 
 	if (size_max)
-		*size_max = pci_resource_len(ndev->ntb.pdev, bar);
+		*size_max = ntb_epf_mw_size(ndev, bar);
 
 	return 0;
 }
@@ -707,7 +724,7 @@ static int ntb_epf_mw_set_trans(struct ntb_dev *ntb, int pidx, int idx,
 	if (bar < 0)
 		return bar;
 
-	mw_size = pci_resource_len(ntb->pdev, bar);
+	mw_size = ntb_epf_mw_size(ndev, bar);
 
 	if (size > mw_size) {
 		dev_err(dev, "Size:%pa is greater than the MW size %pa\n",
@@ -739,21 +756,20 @@ static int ntb_epf_peer_mw_get_addr(struct ntb_dev *ntb, int idx,
 				    phys_addr_t *base, resource_size_t *size)
 {
 	struct ntb_epf_dev *ndev = ntb_ndev(ntb);
-	u32 offset = 0;
+	resource_size_t offset;
 	int bar;
 
-	if (idx == 0)
-		offset = readl(ndev->ctrl_reg + NTB_EPF_CTRL(mw1_offset));
-
 	bar = ntb_epf_mw_to_bar(ndev, idx);
 	if (bar < 0)
 		return bar;
 
+	offset = ntb_epf_mw_offset(ndev, idx);
+
 	if (base)
 		*base = pci_resource_start(ndev->ntb.pdev, bar) + offset;
 
 	if (size)
-		*size = pci_resource_len(ndev->ntb.pdev, bar) - offset;
+		*size = ntb_epf_mw_size(ndev, bar) - offset;
 
 	return 0;
 }
@@ -851,6 +867,7 @@ static int ntb_epf_init_dev(struct ntb_epf_dev *ndev)
 {
 	struct device *dev = ndev->dev;
 	int ret;
+	int i;
 
 	ndev->mw_count = readl(ndev->ctrl_reg + NTB_EPF_CTRL(num_mws));
 	if (ndev->mw_count > NTB_EPF_MAX_MW_COUNT) {
@@ -862,6 +879,18 @@ static int ntb_epf_init_dev(struct ntb_epf_dev *ndev)
 		dev_err(dev, "Invalid endpoint DMA layout\n");
 		return ret;
 	}
+	if (ndev->dma.submap.size) {
+		for (i = 0; i < ndev->mw_count; i++) {
+			int bar = ntb_epf_mw_to_bar(ndev, i);
+
+			if (bar == ndev->dma.submap.bar &&
+			    ntb_epf_mw_size(ndev, bar) <=
+			    ntb_epf_mw_offset(ndev, i)) {
+				dev_err(dev, "Invalid DMA/MW boundary\n");
+				return -EINVAL;
+			}
+		}
+	}
 
 	/* One Link interrupt and rest doorbell interrupt */
 	ret = ntb_epf_init_isr(ndev, NTB_EPF_MIN_DB_COUNT + 1,
diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c b/drivers/pci/endpoint/functions/pci-epf-vntb.c
index ac83af54122f..89f828234ca7 100644
--- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
+++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
@@ -84,12 +84,13 @@ enum epf_irq_slot {
 #define MIN_DB_COUNT			(EPF_IRQ_DB_START + 1)
 
 struct epf_ntb_dma {
+	struct mutex lock; /* Serialize DMA submap and MW updates */
 	struct epf_ntb_dma_ctrl ctrl;
 	struct dma_chan *dchan[EDMA_MAX_RD_CH];
 	void *bar_scratch;
 	dma_addr_t bar_scratch_phys;
 	size_t bar_scratch_size;
-	struct pci_epf_bar_submap submap[EDMA_MAX_RD_CH + 2];
+	struct pci_epf_bar_submap submap[EDMA_MAX_RD_CH + 3];
 	struct pci_epf_bar_submap *reg_submap;
 	unsigned int num_submap;
 	u16 rd_ch_cnt;
@@ -229,6 +230,22 @@ static bool epf_ntb_is_bar_used(struct epf_ntb *ntb,
 	return false;
 }
 
+static u64 epf_ntb_dma_bar_offset(struct epf_ntb *ntb, enum pci_barno barno)
+{
+	unsigned int i;
+
+	for (i = 0; i < ntb->num_mws; i++)
+		if (ntb->epf_ntb_bar[BAR_MW1 + i] == barno)
+			return ntb->mws_size[i];
+
+	return 0;
+}
+
+static bool epf_ntb_dma_shares_bar(struct epf_ntb *ntb, enum pci_barno barno)
+{
+	return ntb->dma && ntb->epf_ntb_bar[BAR_DMA] == barno;
+}
+
 struct epf_ntb_dma_filter {
 	struct device *dev;
 	int chan_id;
@@ -353,6 +370,7 @@ static int epf_ntb_dw_edma_collect(struct epf_ntb *ntb,
 	unsigned int i;
 	size_t align;
 	u32 next = 0;
+	u64 offset;
 	int ret;
 
 	if (ctrl->u.dma_ctrl.reg_layout_data != EDMA_MF_EDMA_UNROLL)
@@ -371,10 +389,31 @@ static int epf_ntb_dw_edma_collect(struct epf_ntb *ntb,
 	if (!is_power_of_2(align))
 		return -EINVAL;
 
-	if (epf_ntb_is_bar_used(ntb, barno) ||
-	    pci_epc_get_next_free_bar(features, barno) != barno)
+	if (barno == ntb->epf_ntb_bar[BAR_CONFIG] ||
+	    barno == ntb->epf_ntb_bar[BAR_DB])
 		return -EINVAL;
 
+	offset = epf_ntb_dma_bar_offset(ntb, barno);
+	if (!offset &&
+	    (epf_ntb_is_bar_used(ntb, barno) ||
+	     pci_epc_get_next_free_bar(features, barno) != barno))
+		return -EINVAL;
+	if (offset > U32_MAX)
+		return -EOVERFLOW;
+	if (offset && !is_power_of_2(offset))
+		return -EINVAL;
+	dma->ctrl.submap.offset = offset;
+	next = offset;
+	if (next) {
+		/*
+		 * submap[0] covers the MW prefix. Keep its temporary
+		 * target at address 0 until the MW translation is
+		 * installed.
+		 */
+		dma->submap[0].size = next;
+		dma->num_submap = 1;
+	}
+
 	dma->ctrl.magic = EPF_NTB_DMA_MAGIC;
 	dma->ctrl.revision = EPF_NTB_DMA_REVISION;
 	dma->ctrl.type = EPF_NTB_DMA_TYPE_DW_EDMA;
@@ -408,7 +447,7 @@ static int epf_ntb_dw_edma_collect(struct epf_ntb *ntb,
 		chan->desc_addr_lo = lower_32_bits(dma_addr);
 		chan->desc_addr_hi = upper_32_bits(dma_addr);
 	}
-	dma->ctrl.submap.size = next;
+	dma->ctrl.submap.size = next - dma->ctrl.submap.offset;
 
 	dma_dev = ntb->epf->epc->dev.parent;
 	for (i = 0; i < dma->rd_ch_cnt; i++) {
@@ -481,6 +520,8 @@ static int epf_ntb_dma_collect(struct epf_ntb *ntb)
 	if (!dma)
 		return -ENOMEM;
 
+	mutex_init(&dma->lock);
+
 	switch (ctrl->u.dma_ctrl.reg_layout) {
 	case PCI_EPC_AUX_DMA_REG_LAYOUT_DW_EDMA:
 		ret = epf_ntb_dw_edma_collect(ntb, dma, ctrl, resources, count);
@@ -551,7 +592,7 @@ static int epf_ntb_dma_bar_init(struct epf_ntb *ntb)
 		return -EOPNOTSUPP;
 
 	barno = ntb->epf_ntb_bar[BAR_DMA];
-	mapped_size = dma->ctrl.submap.size;
+	mapped_size = dma->ctrl.submap.offset + dma->ctrl.submap.size;
 	/*
 	 * Submaps cannot be installed until the host assigns the BAR address.
 	 * Use address 0 for the temporary BAR Match Mode mapping, as is done
@@ -607,21 +648,25 @@ static void epf_ntb_dma_bar_clear(struct epf_ntb *ntb)
 	memset(bar, 0, sizeof(*bar));
 }
 
-static int epf_ntb_dma_set_bar(struct epf_ntb *ntb)
+static int epf_ntb_dma_set_bar_locked(struct epf_ntb *ntb,
+				      const dma_addr_t *mw_addr)
 {
 	struct pci_epf_bar_submap *old_submap;
 	struct epf_ntb_dma *dma = ntb->dma;
 	unsigned int old_num_submap;
 	struct pci_epf_bar *bar;
+	dma_addr_t old_mw_addr;
 	int restore, ret;
-
-	if (!dma)
-		return 0;
+	lockdep_assert_held(&dma->lock);
 
 	bar = &ntb->epf->bar[ntb->epf_ntb_bar[BAR_DMA]];
 
 	old_submap = bar->submap;
 	old_num_submap = bar->num_submap;
+	if (mw_addr) {
+		old_mw_addr = dma->submap[0].phys_addr;
+		dma->submap[0].phys_addr = *mw_addr;
+	}
 	bar->submap = dma->submap;
 	bar->num_submap = dma->num_submap;
 
@@ -631,6 +676,8 @@ static int epf_ntb_dma_set_bar(struct epf_ntb *ntb)
 		return 0;
 
 	/* A failed dynamic update may have already removed the old mapping. */
+	if (mw_addr)
+		dma->submap[0].phys_addr = old_mw_addr;
 	bar->submap = old_submap;
 	bar->num_submap = old_num_submap;
 	restore = pci_epc_set_bar(ntb->epf->epc, ntb->epf->func_no,
@@ -642,6 +689,18 @@ static int epf_ntb_dma_set_bar(struct epf_ntb *ntb)
 	return ret;
 }
 
+static int epf_ntb_dma_set_bar(struct epf_ntb *ntb)
+{
+	struct epf_ntb_dma *dma = ntb->dma;
+
+	if (!dma)
+		return 0;
+
+	guard(mutex)(&dma->lock);
+
+	return epf_ntb_dma_set_bar_locked(ntb, NULL);
+}
+
 /**
  * epf_ntb_configure_mw() - Configure the Outbound Address Space for VHOST
  *   to access the memory window of HOST
@@ -1269,6 +1328,7 @@ static void epf_ntb_db_bar_clear(struct epf_ntb *ntb)
  */
 static int epf_ntb_mw_bar_init(struct epf_ntb *ntb)
 {
+	bool shared;
 	int ret = 0;
 	int i;
 	u64 size;
@@ -1278,22 +1338,25 @@ static int epf_ntb_mw_bar_init(struct epf_ntb *ntb)
 	for (i = 0; i < ntb->num_mws; i++) {
 		size = ntb->mws_size[i];
 		barno = ntb->epf_ntb_bar[BAR_MW1 + i];
-
-		ntb->epf->bar[barno].barno = barno;
-		ntb->epf->bar[barno].size = size;
-		ntb->epf->bar[barno].addr = NULL;
-		ntb->epf->bar[barno].phys_addr = 0;
-		ntb->epf->bar[barno].flags |= upper_32_bits(size) ?
-				PCI_BASE_ADDRESS_MEM_TYPE_64 :
-				PCI_BASE_ADDRESS_MEM_TYPE_32;
-
-		ret = pci_epc_set_bar(ntb->epf->epc,
-				      ntb->epf->func_no,
-				      ntb->epf->vfunc_no,
-				      &ntb->epf->bar[barno]);
-		if (ret) {
-			dev_err(dev, "MW set failed\n");
-			goto err_alloc_mem;
+		shared = epf_ntb_dma_shares_bar(ntb, barno);
+
+		if (!shared) {
+			ntb->epf->bar[barno].barno = barno;
+			ntb->epf->bar[barno].size = size;
+			ntb->epf->bar[barno].addr = NULL;
+			ntb->epf->bar[barno].phys_addr = 0;
+			ntb->epf->bar[barno].flags |= upper_32_bits(size) ?
+					PCI_BASE_ADDRESS_MEM_TYPE_64 :
+					PCI_BASE_ADDRESS_MEM_TYPE_32;
+
+			ret = pci_epc_set_bar(ntb->epf->epc,
+					      ntb->epf->func_no,
+					      ntb->epf->vfunc_no,
+					      &ntb->epf->bar[barno]);
+			if (ret) {
+				dev_err(dev, "MW set failed\n");
+				goto err_alloc_mem;
+			}
 		}
 
 		/* Allocate EPC outbound memory windows to vpci vntb device */
@@ -1310,10 +1373,11 @@ static int epf_ntb_mw_bar_init(struct epf_ntb *ntb)
 	return ret;
 
 err_set_bar:
-	pci_epc_clear_bar(ntb->epf->epc,
-			  ntb->epf->func_no,
-			  ntb->epf->vfunc_no,
-			  &ntb->epf->bar[barno]);
+	if (!shared)
+		pci_epc_clear_bar(ntb->epf->epc,
+				  ntb->epf->func_no,
+				  ntb->epf->vfunc_no,
+				  &ntb->epf->bar[barno]);
 err_alloc_mem:
 	epf_ntb_mw_bar_clear(ntb, i);
 	return ret;
@@ -1331,10 +1395,11 @@ static void epf_ntb_mw_bar_clear(struct epf_ntb *ntb, int num_mws)
 
 	for (i = 0; i < num_mws; i++) {
 		barno = ntb->epf_ntb_bar[BAR_MW1 + i];
-		pci_epc_clear_bar(ntb->epf->epc,
-				  ntb->epf->func_no,
-				  ntb->epf->vfunc_no,
-				  &ntb->epf->bar[barno]);
+		if (!epf_ntb_dma_shares_bar(ntb, barno))
+			pci_epc_clear_bar(ntb->epf->epc,
+					  ntb->epf->func_no,
+					  ntb->epf->vfunc_no,
+					  &ntb->epf->bar[barno]);
 
 		pci_epc_mem_free_addr(ntb->epf->epc,
 				      ntb->vpci_mw_phy[i],
@@ -1936,6 +2001,16 @@ static int vntb_epf_mw_set_trans(struct ntb_dev *ndev, int pidx, int idx,
 	dev = &ndev->dev;
 	barno = ntb->epf_ntb_bar[BAR_MW1 + idx];
 	epf_bar = &ntb->epf->bar[barno];
+	if (epf_ntb_dma_shares_bar(ntb, barno)) {
+		/* DMA submaps start after the configured MW size. */
+		if (size != ntb->mws_size[idx])
+			return -EINVAL;
+
+		guard(mutex)(&ntb->dma->lock);
+
+		return epf_ntb_dma_set_bar_locked(ntb, &addr);
+	}
+
 	epf_bar->phys_addr = addr;
 	epf_bar->barno = barno;
 	epf_bar->size = size;
@@ -2134,15 +2209,17 @@ static int vntb_epf_mw_get_align(struct ntb_dev *ndev, int pidx, int idx,
 			resource_size_t *size_max)
 {
 	struct epf_ntb *ntb = ntb_ndev(ndev);
+	enum pci_barno barno = ntb->epf_ntb_bar[BAR_MW1 + idx];
+	u64 size = ntb->mws_size[idx];
 
 	if (addr_align)
 		*addr_align = SZ_4K;
 
 	if (size_align)
-		*size_align = 1;
+		*size_align = epf_ntb_dma_shares_bar(ntb, barno) ? size : 1;
 
 	if (size_max)
-		*size_max = ntb->mws_size[idx];
+		*size_max = size;
 
 	return 0;
 }
-- 
2.54.0