linux-kernel - [PATCH 4.9 045/117] PCI: rcar: Fix 64bit MSI message address handling

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Message-Id: <20190620174354.672833798@linuxfoundation.org>
Date:   Thu, 20 Jun 2019 19:56:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Marek Vasut <marek.vasut+renesas@...il.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Simon Horman <horms+renesas@...ge.net.au>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Phil Edworthy <phil.edworthy@...esas.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        linux-renesas-soc@...r.kernel.org, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 045/117] PCI: rcar: Fix 64bit MSI message address handling

[ Upstream commit 954b4b752a4c4e963b017ed8cef4c453c5ed308d ]

The MSI message address in the RC address space can be 64 bit. The
R-Car PCIe RC supports such a 64bit MSI message address as well.
The code currently uses virt_to_phys(__get_free_pages()) to obtain
a reserved page for the MSI message address, and the return value
of which can be a 64 bit physical address on 64 bit system.

However, the driver only programs PCIEMSIALR register with the bottom
32 bits of the virt_to_phys(__get_free_pages()) return value and does
not program the top 32 bits into PCIEMSIAUR, but rather programs the
PCIEMSIAUR register with 0x0. This worked fine on older 32 bit R-Car
SoCs, however may fail on new 64 bit R-Car SoCs.

Since from a PCIe controller perspective, an inbound MSI is a memory
write to a special address (in case of this controller, defined by
the value in PCIEMSIAUR:PCIEMSIALR), which triggers an interrupt, but
never hits the DRAM _and_ because allocation of an MSI by a PCIe card
driver obtains the MSI message address by reading PCIEMSIAUR:PCIEMSIALR
in rcar_msi_setup_irqs(), incorrectly programmed PCIEMSIAUR cannot
cause memory corruption or other issues.

There is however the possibility that if virt_to_phys(__get_free_pages())
returned address above the 32bit boundary _and_ PCIEMSIAUR was programmed
to 0x0 _and_ if the system had physical RAM at the address matching the
value of PCIEMSIALR, a PCIe card driver could allocate a buffer with a
physical address matching the value of PCIEMSIALR and a remote write to
such a buffer by a PCIe card would trigger a spurious MSI.

Fixes: e015f88c368d ("PCI: rcar: Add support for R-Car H3 to pcie-rcar")
Signed-off-by: Marek Vasut <marek.vasut+renesas@...il.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Reviewed-by: Simon Horman <horms+renesas@...ge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
Cc: Geert Uytterhoeven <geert+renesas@...der.be>
Cc: Phil Edworthy <phil.edworthy@...esas.com>
Cc: Simon Horman <horms+renesas@...ge.net.au>
Cc: Wolfram Sang <wsa@...-dreams.de>
Cc: linux-renesas-soc@...r.kernel.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/pci/host/pcie-rcar.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/host/pcie-rcar.c b/drivers/pci/host/pcie-rcar.c
index 77d931178178..7f6b454bca65 100644
--- a/drivers/pci/host/pcie-rcar.c
+++ b/drivers/pci/host/pcie-rcar.c
@@ -847,7 +847,7 @@ static int rcar_pcie_enable_msi(struct rcar_pcie *pcie)
 {
 	struct device *dev = pcie->dev;
 	struct rcar_msi *msi = &pcie->msi;
-	unsigned long base;
+	phys_addr_t base;
 	int err, i;

 	mutex_init(&msi->lock);
@@ -892,8 +892,8 @@ static int rcar_pcie_enable_msi(struct rcar_pcie *pcie)
 	}
 	base = virt_to_phys((void *)msi->pages);

-	rcar_pci_write_reg(pcie, base | MSIFE, PCIEMSIALR);
-	rcar_pci_write_reg(pcie, 0, PCIEMSIAUR);
+	rcar_pci_write_reg(pcie, lower_32_bits(base) | MSIFE, PCIEMSIALR);
+	rcar_pci_write_reg(pcie, upper_32_bits(base), PCIEMSIAUR);

 	/* enable all MSI interrupts */
 	rcar_pci_write_reg(pcie, 0xffffffff, PCIEMSIIER);
-- 
2.20.1