linux-kernel - [PATCH 1/7] x86/hyperv: Fix output argument to hypercall that changes page visibility

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Message-Id: <20250226200612.2062-2-mhklinux@outlook.com>
Date: Wed, 26 Feb 2025 12:06:06 -0800
From: mhkelley58@...il.com
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Subject: [PATCH 1/7] x86/hyperv: Fix output argument to hypercall that changes page visibility

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

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>
---
I have not provided a "Fixes:" tag because the error causes no impact.
There's no value in backporting the fix.

 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 dd68d9ad9b22..ec7880271cf9 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -464,7 +464,6 @@ 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;
 
@@ -493,7 +492,7 @@ 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))
-- 
2.25.1