linux-kernel - [PATCH v3 18/20] vmw_balloon: support 64-bit memory limit

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Date:   Wed, 26 Sep 2018 12:13:34 -0700
From:   Nadav Amit <namit@...are.com>
To:     Arnd Bergmann <arnd@...db.de>, <gregkh@...uxfoundation.org>
CC:     Xavier Deguillard <xdeguillard@...are.com>,
        <linux-kernel@...r.kernel.org>, Nadav Amit <namit@...are.com>
Subject: [PATCH v3 18/20] vmw_balloon: support 64-bit memory limit

From: Xavier Deguillard <xdeguillard@...are.com>

Currently, the balloon driver would fail to run if memory is greater
than 16TB of vRAM. Previous patches have already converted the balloon
target and size to 64-bit, so all that is left to do add is to avoid
asserting memory is smaller than 16TB if the hypervisor supports 64-bits
target.

The driver advertises a new capability VMW_BALLOON_64_BITS_TARGET.
Hypervisors that support 16TB of memory or more will report that this
capability is enabled.

Signed-off-by: Xavier Deguillard <xdeguillard@...are.com>
Signed-off-by: Nadav Amit <namit@...are.com>
---
 drivers/misc/vmw_balloon.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
index d3921a1334ec..4c9c171325c3 100644
--- a/drivers/misc/vmw_balloon.c
+++ b/drivers/misc/vmw_balloon.c
@@ -61,15 +61,26 @@ enum vmwballoon_capabilities {
 	VMW_BALLOON_BATCHED_CMDS		= (1 << 2),
 	VMW_BALLOON_BATCHED_2M_CMDS		= (1 << 3),
 	VMW_BALLOON_SIGNALLED_WAKEUP_CMD	= (1 << 4),
+	VMW_BALLOON_64_BIT_TARGET		= (1 << 5)
 };
 
-#define VMW_BALLOON_CAPABILITIES	(VMW_BALLOON_BASIC_CMDS \
+#define VMW_BALLOON_CAPABILITIES_COMMON	(VMW_BALLOON_BASIC_CMDS \
 					| VMW_BALLOON_BATCHED_CMDS \
 					| VMW_BALLOON_BATCHED_2M_CMDS \
 					| VMW_BALLOON_SIGNALLED_WAKEUP_CMD)
 
 #define VMW_BALLOON_2M_ORDER		(PMD_SHIFT - PAGE_SHIFT)
 
+/*
+ * 64-bit targets are only supported in 64-bit
+ */
+#ifdef CONFIG_64BIT
+#define VMW_BALLOON_CAPABILITIES	(VMW_BALLOON_CAPABILITIES_COMMON \
+					| VMW_BALLOON_64_BIT_TARGET)
+#else
+#define VMW_BALLOON_CAPABILITIES	VMW_BALLOON_CAPABILITIES_COMMON
+#endif
+
 enum vmballoon_page_size_type {
 	VMW_BALLOON_4K_PAGE,
 	VMW_BALLOON_2M_PAGE,
@@ -565,8 +576,9 @@ static int vmballoon_send_get_target(struct vmballoon *b)
 
 	limit = totalram_pages;
 
-	/* Ensure limit fits in 32-bits */
-	if (limit != (u32)limit)
+	/* Ensure limit fits in 32-bits if 64-bit targets are not supported */
+	if (!(b->capabilities & VMW_BALLOON_64_BIT_TARGET) &&
+	    limit != (u32)limit)
 		return -EINVAL;
 
 	status = vmballoon_cmd(b, VMW_BALLOON_CMD_GET_TARGET, limit, 0);
-- 
2.17.1