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Marek Vasut
9b116cfce9
[ Upstream commit954b4b752a] 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:e015f88c36("PCI: rcar: Add support for R-Car H3 to pcie-rcar") Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Reviewed-by: Simon Horman <horms+renesas@verge.net.au> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Cc: Geert Uytterhoeven <geert+renesas@glider.be> Cc: Phil Edworthy <phil.edworthy@renesas.com> Cc: Simon Horman <horms+renesas@verge.net.au> Cc: Wolfram Sang <wsa@the-dreams.de> Cc: linux-renesas-soc@vger.kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.