linux-kernel - [PATCH v4 04/29] drm/i915/gvt: Don't try to unpin an empty page range

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Message-ID: <20230729013535.1070024-5-seanjc@google.com>
Date:   Fri, 28 Jul 2023 18:35:10 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Zhenyu Wang <zhenyuw@...ux.intel.com>,
        Zhi Wang <zhi.a.wang@...el.com>
Cc:     kvm@...r.kernel.org, intel-gvt-dev@...ts.freedesktop.org,
        intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Yan Zhao <yan.y.zhao@...el.com>,
        Yongwei Ma <yongwei.ma@...el.com>,
        Ben Gardon <bgardon@...gle.com>
Subject: [PATCH v4 04/29] drm/i915/gvt: Don't try to unpin an empty page range

From: Yan Zhao <yan.y.zhao@...el.com>

Attempt to unpin pages in the error path of gvt_pin_guest_page() if and
only if at least one page was successfully pinned.  Unpinning doesn't
cause functional problems, but vfio_device_container_unpin_pages()
rightfully warns about being asked to unpin zero pages.

Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
[sean: write changelog]
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 drivers/gpu/drm/i915/gvt/kvmgt.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
index 429f0f993a13..0366a699baf5 100644
--- a/drivers/gpu/drm/i915/gvt/kvmgt.c
+++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
@@ -172,7 +172,8 @@ static int gvt_pin_guest_page(struct intel_vgpu *vgpu, unsigned long gfn,
 	*page = base_page;
 	return 0;
 err:
-	gvt_unpin_guest_page(vgpu, gfn, npage * PAGE_SIZE);
+	if (npage)
+		gvt_unpin_guest_page(vgpu, gfn, npage * PAGE_SIZE);
 	return ret;
 }
 
-- 
2.41.0.487.g6d72f3e995-goog