Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Mike Rapoport <rppt@linux.ibm.com>,
        Christoph Hellwig <hch@lst.de>,
        David Hildenbrand <david@redhat.com>,
        Will Deacon <will@kernel.org>,
        Georgi Djakov <quic_c_gdjako@quicinc.com>
Subject: [PATCH 5.15 006/124] dma-mapping: remove bogus test for pfn_valid from dma_map_resource
Date:   Tue, 26 Apr 2022 10:20:07 +0200
Message-Id: <20220426081747.474819433@linuxfoundation.org>
In-Reply-To: <20220426081747.286685339@linuxfoundation.org>
References: <20220426081747.286685339@linuxfoundation.org>
User-Agent: quilt/0.66
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Mike Rapoport <rppt@linux.ibm.com>

commit a9c38c5d267cb94871dfa2de5539c92025c855d7 upstream.

dma_map_resource() uses pfn_valid() to ensure the range is not RAM.
However, pfn_valid() only checks for availability of the memory map for a
PFN but it does not ensure that the PFN is actually backed by RAM.

As dma_map_resource() is the only method in DMA mapping APIs that has this
check, simply drop the pfn_valid() test from dma_map_resource().

Link: https://lore.kernel.org/all/20210824173741.GC623@arm.com/
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/r/20210930013039.11260-2-rppt@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Fixes: 859a85ddf90e ("mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE")
Link: https://lore.kernel.org/r/Yl0IZWT2nsiYtqBT@linux.ibm.com
Signed-off-by: Georgi Djakov <quic_c_gdjako@quicinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/dma/mapping.c |    4 ----
 1 file changed, 4 deletions(-)

--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -296,10 +296,6 @@ dma_addr_t dma_map_resource(struct devic
 	if (WARN_ON_ONCE(!dev->dma_mask))
 		return DMA_MAPPING_ERROR;
 
-	/* Don't allow RAM to be mapped */
-	if (WARN_ON_ONCE(pfn_valid(PHYS_PFN(phys_addr))))
-		return DMA_MAPPING_ERROR;
-
 	if (dma_map_direct(dev, ops))
 		addr = dma_direct_map_resource(dev, phys_addr, size, dir, attrs);
 	else if (ops->map_resource)