linux-kernel - [PATCH AUTOSEL 6.13 08/16] x86/hyperv: Fix output argument to hypercall that changes page visibility

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Message-Id: <20250317163725.1892824-8-sashal@kernel.org>
Date: Mon, 17 Mar 2025 12:37:17 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Michael Kelley <mhklinux@...look.com>,
	Nuno Das Neves <nunodasneves@...ux.microsoft.com>,
	Wei Liu <wei.liu@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	kys@...rosoft.com,
	haiyangz@...rosoft.com,
	decui@...rosoft.com,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	linux-hyperv@...r.kernel.org
Subject: [PATCH AUTOSEL 6.13 08/16] x86/hyperv: Fix output argument to hypercall that changes page visibility

From: Michael Kelley <mhklinux@...look.com>

[ Upstream commit 09beefefb57bbc3a06d98f319d85db4d719d7bcb ]

The hypercall in hv_mark_gpa_visibility() is invoked with an input
argument and an output argument. The output argument ostensibly returns
the number of pages that were processed. But in fact, the hypercall does
not provide any output, so the output argument is spurious.

The spurious argument is harmless because Hyper-V ignores it, but in the
interest of correctness and to avoid the potential for future problems,
remove it.

Signed-off-by: Michael Kelley <mhklinux@...look.com>
Reviewed-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
Link: https://lore.kernel.org/r/20250226200612.2062-2-mhklinux@outlook.com
Signed-off-by: Wei Liu <wei.liu@...nel.org>
Message-ID: <20250226200612.2062-2-mhklinux@...look.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/hyperv/ivm.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index 60fc3ed728304..aa8befc4d9013 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -465,7 +465,6 @@ static int hv_mark_gpa_visibility(u16 count, const u64 pfn[],
 			   enum hv_mem_host_visibility visibility)
 {
 	struct hv_gpa_range_for_visibility *input;
-	u16 pages_processed;
 	u64 hv_status;
 	unsigned long flags;
 
@@ -494,7 +493,7 @@ static int hv_mark_gpa_visibility(u16 count, const u64 pfn[],
 	memcpy((void *)input->gpa_page_list, pfn, count * sizeof(*pfn));
 	hv_status = hv_do_rep_hypercall(
 			HVCALL_MODIFY_SPARSE_GPA_PAGE_HOST_VISIBILITY, count,
-			0, input, &pages_processed);
+			0, input, NULL);
 	local_irq_restore(flags);
 
 	if (hv_result_success(hv_status))
-- 
2.39.5