[ 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@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 --- 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 fad57d068db3..2b0a1f3b8265 100644 --- a/drivers/pci/host/pcie-rcar.c +++ b/drivers/pci/host/pcie-rcar.c @@ -849,7 +849,7 @@ 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); @@ -894,8 +894,8 @@ 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);