linux-kernel - [PATCH v2 1/7] vmw_balloon: fix inflation of 64-bit GFNs

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Message-ID: <20180613135412.81660-2-namit@vmware.com>
Date:   Wed, 13 Jun 2018 06:54:06 -0700
From:   Nadav Amit <namit@...are.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     Xavier Deguillard <xdeguillard@...are.com>,
        <linux-kernel@...r.kernel.org>, Arnd Bergmann <arnd@...db.de>,
        Nadav Amit <namit@...are.com>, <stable@...r.kernel.org>
Subject: [PATCH v2 1/7] vmw_balloon: fix inflation of 64-bit GFNs

When balloon batching is not supported by the hypervisor, the guest
frame number (GFN) must fit in 32-bit. However, due to a bug, this check
was mistakenly ignored. In practice, when total RAM is greater than
16TB, the balloon does not work currently, making this bug unlikely to
happen.

Fixes: ef0f8f112984 ("VMware balloon: partially inline vmballoon_reserve_page.")

Cc: stable@...r.kernel.org
Reviewed-by: Xavier Deguillard <xdeguillard@...are.com>
Signed-off-by: Nadav Amit <namit@...are.com>
---
 drivers/misc/vmw_balloon.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index efd733472a35..28e77ab1e136 100644
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -450,7 +450,7 @@ static int vmballoon_send_lock_page(struct vmballoon *b, unsigned long pfn,
 
 	pfn32 = (u32)pfn;
 	if (pfn32 != pfn)
-		return -1;
+		return -EINVAL;
 
 	STATS_INC(b->stats.lock[false]);
 
@@ -460,7 +460,7 @@ static int vmballoon_send_lock_page(struct vmballoon *b, unsigned long pfn,
 
 	pr_debug("%s - ppn %lx, hv returns %ld\n", __func__, pfn, status);
 	STATS_INC(b->stats.lock_fail[false]);
-	return 1;
+	return -EIO;
 }
 
 static int vmballoon_send_batched_lock(struct vmballoon *b,
@@ -597,11 +597,12 @@ static int vmballoon_lock_page(struct vmballoon *b, unsigned int num_pages,
 
 	locked = vmballoon_send_lock_page(b, page_to_pfn(page), &hv_status,
 								target);
-	if (locked > 0) {
+	if (locked) {
 		STATS_INC(b->stats.refused_alloc[false]);
 
-		if (hv_status == VMW_BALLOON_ERROR_RESET ||
-				hv_status == VMW_BALLOON_ERROR_PPN_NOTNEEDED) {
+		if (locked == -EIO &&
+		    (hv_status == VMW_BALLOON_ERROR_RESET ||
+		     hv_status == VMW_BALLOON_ERROR_PPN_NOTNEEDED)) {
 			vmballoon_free_page(page, false);
 			return -EIO;
 		}
@@ -617,7 +618,7 @@ static int vmballoon_lock_page(struct vmballoon *b, unsigned int num_pages,
 		} else {
 			vmballoon_free_page(page, false);
 		}
-		return -EIO;
+		return locked;
 	}
 
 	/* track allocated page */
-- 
2.17.0