linux-kernel - [PATCH V2 2/2] xen/virtio: Convert PAGE_SIZE/PAGE_SHIFT/PFN

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Date:   Sat,  8 Oct 2022 18:10:13 +0300
From:   Oleksandr Tyshchenko <olekstysh@...il.com>
To:     xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org
Cc:     Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Juergen Gross <jgross@...e.com>,
        Xenia Ragiadakou <burzalodowa@...il.com>
Subject: [PATCH V2 2/2] xen/virtio: Convert PAGE_SIZE/PAGE_SHIFT/PFN_UP to Xen counterparts

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>

Currently, a grant ref is always based on the Xen page granularity
(4KB), and guest commonly uses the same page granularity.
But the guest may use a different page granularity (i.e 64KB).
So adopt the code to be able to deal with it.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
---
Cc: Juergen Gross <jgross@...e.com>
Cc: Xenia Ragiadakou <burzalodowa@...il.com>

Changes V1 -> V2:
   - update commit description
   - rebase
   - use xen_offset_in_page() in xen_grant_dma_map(unmap)_page()

Previous discussion is at:
https://lore.kernel.org/xen-devel/20221006120912.1948459-1-olekstysh@gmail.com/
---
 drivers/xen/grant-dma-ops.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
index 1d018e3a68a0..aff0f95ed954 100644
--- a/drivers/xen/grant-dma-ops.c
+++ b/drivers/xen/grant-dma-ops.c
@@ -31,12 +31,12 @@ static DEFINE_XARRAY_FLAGS(xen_grant_dma_devices, XA_FLAGS_LOCK_IRQ);
 
 static inline dma_addr_t grant_to_dma(grant_ref_t grant)
 {
-	return XEN_GRANT_DMA_ADDR_OFF | ((dma_addr_t)grant << PAGE_SHIFT);
+	return XEN_GRANT_DMA_ADDR_OFF | ((dma_addr_t)grant << XEN_PAGE_SHIFT);
 }
 
 static inline grant_ref_t dma_to_grant(dma_addr_t dma)
 {
-	return (grant_ref_t)((dma & ~XEN_GRANT_DMA_ADDR_OFF) >> PAGE_SHIFT);
+	return (grant_ref_t)((dma & ~XEN_GRANT_DMA_ADDR_OFF) >> XEN_PAGE_SHIFT);
 }
 
 static struct xen_grant_dma_data *find_xen_grant_dma_data(struct device *dev)
@@ -79,7 +79,7 @@ static void *xen_grant_dma_alloc(struct device *dev, size_t size,
 				 unsigned long attrs)
 {
 	struct xen_grant_dma_data *data;
-	unsigned int i, n_pages = PFN_UP(size);
+	unsigned int i, n_pages = XEN_PFN_UP(size);
 	unsigned long pfn;
 	grant_ref_t grant;
 	void *ret;
@@ -91,14 +91,14 @@ static void *xen_grant_dma_alloc(struct device *dev, size_t size,
 	if (unlikely(data->broken))
 		return NULL;
 
-	ret = alloc_pages_exact(n_pages * PAGE_SIZE, gfp);
+	ret = alloc_pages_exact(n_pages * XEN_PAGE_SIZE, gfp);
 	if (!ret)
 		return NULL;
 
 	pfn = virt_to_pfn(ret);
 
 	if (gnttab_alloc_grant_reference_seq(n_pages, &grant)) {
-		free_pages_exact(ret, n_pages * PAGE_SIZE);
+		free_pages_exact(ret, n_pages * XEN_PAGE_SIZE);
 		return NULL;
 	}
 
@@ -116,7 +116,7 @@ static void xen_grant_dma_free(struct device *dev, size_t size, void *vaddr,
 			       dma_addr_t dma_handle, unsigned long attrs)
 {
 	struct xen_grant_dma_data *data;
-	unsigned int i, n_pages = PFN_UP(size);
+	unsigned int i, n_pages = XEN_PFN_UP(size);
 	grant_ref_t grant;
 
 	data = find_xen_grant_dma_data(dev);
@@ -138,7 +138,7 @@ static void xen_grant_dma_free(struct device *dev, size_t size, void *vaddr,
 
 	gnttab_free_grant_reference_seq(grant, n_pages);
 
-	free_pages_exact(vaddr, n_pages * PAGE_SIZE);
+	free_pages_exact(vaddr, n_pages * XEN_PAGE_SIZE);
 }
 
 static struct page *xen_grant_dma_alloc_pages(struct device *dev, size_t size,
@@ -168,9 +168,9 @@ static dma_addr_t xen_grant_dma_map_page(struct device *dev, struct page *page,
 					 unsigned long attrs)
 {
 	struct xen_grant_dma_data *data;
-	unsigned long dma_offset = offset_in_page(offset),
-			pfn_offset = PFN_DOWN(offset);
-	unsigned int i, n_pages = PFN_UP(dma_offset + size);
+	unsigned long dma_offset = xen_offset_in_page(offset),
+			pfn_offset = XEN_PFN_DOWN(offset);
+	unsigned int i, n_pages = XEN_PFN_UP(dma_offset + size);
 	grant_ref_t grant;
 	dma_addr_t dma_handle;
 
@@ -203,8 +203,8 @@ static void xen_grant_dma_unmap_page(struct device *dev, dma_addr_t dma_handle,
 				     unsigned long attrs)
 {
 	struct xen_grant_dma_data *data;
-	unsigned long offset = dma_handle & (PAGE_SIZE - 1);
-	unsigned int i, n_pages = PFN_UP(offset + size);
+	unsigned long dma_offset = xen_offset_in_page(dma_handle);
+	unsigned int i, n_pages = XEN_PFN_UP(dma_offset + size);
 	grant_ref_t grant;
 
 	if (WARN_ON(dir == DMA_NONE))
-- 
2.25.1