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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Sasha Levin <sashal@kernel.org>, Sagi Grimberg <sagi@grimberg.me>,
	linux-nvme@lists.infradead.org,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: [PATCH AUTOSEL 5.3 09/99] nvme: retain split access workaround for capability reads
Date: Sat, 26 Oct 2019 09:14:30 -0400	[thread overview]
Message-ID: <20191026131600.2507-9-sashal@kernel.org> (raw)
In-Reply-To: <20191026131600.2507-1-sashal@kernel.org>

From: Ard Biesheuvel <ard.biesheuvel@linaro.org>

[ Upstream commit 3a8ecc935efabdad106b5e06d07b150c394b4465 ]

Commit 7fd8930f26be4

  "nvme: add a common helper to read Identify Controller data"

has re-introduced an issue that we have attempted to work around in the
past, in commit a310acd7a7ea ("NVMe: use split lo_hi_{read,write}q").

The problem is that some PCIe NVMe controllers do not implement 64-bit
outbound accesses correctly, which is why the commit above switched
to using lo_hi_[read|write]q for all 64-bit BAR accesses occuring in
the code.

In the mean time, the NVMe subsystem has been refactored, and now calls
into the PCIe support layer for NVMe via a .reg_read64() method, which
fails to use lo_hi_readq(), and thus reintroduces the problem that the
workaround above aimed to address.

Given that, at the moment, .reg_read64() is only used to read the
capability register [which is known to tolerate split reads], let's
switch .reg_read64() to lo_hi_readq() as well.

This fixes a boot issue on some ARM boxes with NVMe behind a Synopsys
DesignWare PCIe host controller.

Fixes: 7fd8930f26be4 ("nvme: add a common helper to read Identify Controller data")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/nvme/host/pci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 732d5b63ec054..48a71909763be 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2620,7 +2620,7 @@ static int nvme_pci_reg_write32(struct nvme_ctrl *ctrl, u32 off, u32 val)
 
 static int nvme_pci_reg_read64(struct nvme_ctrl *ctrl, u32 off, u64 *val)
 {
-	*val = readq(to_nvme_dev(ctrl)->bar + off);
+	*val = lo_hi_readq(to_nvme_dev(ctrl)->bar + off);
 	return 0;
 }
 
-- 
2.20.1


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  parent reply	other threads:[~2019-10-26 13:16 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20191026131600.2507-1-sashal@kernel.org>
2019-10-26 13:14 ` [PATCH AUTOSEL 5.3 08/99] nvme: fix possible deadlock when nvme_update_formats fails Sasha Levin
2019-10-26 13:14 ` Sasha Levin [this message]
2019-10-26 13:15 ` [PATCH AUTOSEL 5.3 65/99] nvme-pci: Free tagset if no IO queues Sasha Levin
2019-10-26 13:15 ` [PATCH AUTOSEL 5.3 66/99] nvme: Prevent resets during paused controller state Sasha Levin
2019-10-26 13:15 ` [PATCH AUTOSEL 5.3 74/99] nvmet-loop: fix possible leakage during error flow Sasha Levin
2019-10-26 13:15 ` [PATCH AUTOSEL 5.3 75/99] nvme-tcp: " Sasha Levin

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