linux-kernel - [PATCH AUTOSEL 4.9 6/6] xen/xenbus: Fix granting of vmalloc'd memory

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Message-Id: <20200831153150.1024799-6-sashal@kernel.org>
Date:   Mon, 31 Aug 2020 11:31:49 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Simon Leiner <simon@...ner.me>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Juergen Gross <jgross@...e.com>,
        Sasha Levin <sashal@...nel.org>, xen-devel@...ts.xenproject.org
Subject: [PATCH AUTOSEL 4.9 6/6] xen/xenbus: Fix granting of vmalloc'd memory

From: Simon Leiner <simon@...ner.me>

[ Upstream commit d742db70033c745e410523e00522ee0cfe2aa416 ]

On some architectures (like ARM), virt_to_gfn cannot be used for
vmalloc'd memory because of its reliance on virt_to_phys. This patch
introduces a check for vmalloc'd addresses and obtains the PFN using
vmalloc_to_pfn in that case.

Signed-off-by: Simon Leiner <simon@...ner.me>
Reviewed-by: Stefano Stabellini <sstabellini@...nel.org>
Link: https://lore.kernel.org/r/20200825093153.35500-1-simon@leiner.me
Signed-off-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/xen/xenbus/xenbus_client.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index df27cefb2fa35..266f446ba331c 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -384,8 +384,14 @@ int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr,
 	int i, j;
 
 	for (i = 0; i < nr_pages; i++) {
-		err = gnttab_grant_foreign_access(dev->otherend_id,
-						  virt_to_gfn(vaddr), 0);
+		unsigned long gfn;
+
+		if (is_vmalloc_addr(vaddr))
+			gfn = pfn_to_gfn(vmalloc_to_pfn(vaddr));
+		else
+			gfn = virt_to_gfn(vaddr);
+
+		err = gnttab_grant_foreign_access(dev->otherend_id, gfn, 0);
 		if (err < 0) {
 			xenbus_dev_fatal(dev, err,
 					 "granting access to ring page");
-- 
2.25.1