From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933023AbeCMNj7 (ORCPT ); Tue, 13 Mar 2018 09:39:59 -0400 Received: from lelnx194.ext.ti.com ([198.47.27.80]:13231 "EHLO lelnx194.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752381AbeCMNjy (ORCPT ); Tue, 13 Mar 2018 09:39:54 -0400 Subject: Re: [3/3] irqchip/gic-v3: Bounds check redistributor accesses To: Punit Agrawal , CC: , , "Menon, Nishanth" References: <20171011094148.15674-4-punit.agrawal@arm.com> From: Lokesh Vutla Message-ID: <28f9c1cd-e1df-f4db-32b4-c9ca0f0f256a@ti.com> Date: Tue, 13 Mar 2018 19:08:46 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <20171011094148.15674-4-punit.agrawal@arm.com> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi All, On Wednesday 11 October 2017 03:11 PM, Punit Agrawal wrote: > The kernel crashes while iterating over a redistributor that is > in-correctly sized by the platform firmware or doesn't contain the last > record. > > Prevent the crash by checking accesses against the size of the region > provided by the firmware. While we are at it, warn the user about > incorrect region size. > > Signed-off-by: Punit Agrawal > Cc: Marc Zyngier Sorry to bring up an old thread. Just wanted to check what is the status on this series. This will also be useful when we try to boot linux + hypervisor with less number of cores than the SoC supports. For example: - SoC has 4 cores and Linux tries to boot with 2 cores. - then a type-2 hypervisor gets installed. - Hypervisor tries to boot a VM with linux on core 1. Now the VM boot will fail while it iterates over all the GICR regions till GICR_TYPER is found. Hypervisor will trap any accesses to GICR regions of any invalid cpus(cpu 2, cpu 3 in this case). If the $patch is not the right approach, can you suggest on how to handle the above scenario? Thanks and regards, Lokesh > --- > drivers/irqchip/irq-gic-v3.c | 48 ++++++++++++++++++++++++++++++++++++-------- > 1 file changed, 40 insertions(+), 8 deletions(-) > > diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c > index 881d327c53fa..754d936c95e5 100644 > --- a/drivers/irqchip/irq-gic-v3.c > +++ b/drivers/irqchip/irq-gic-v3.c > @@ -429,11 +429,21 @@ static int gic_iterate_rdists(int (*fn)(struct redist_region *, void __iomem *)) > int i; > > for (i = 0; i < gic_data.nr_redist_regions; i++) { > - void __iomem *ptr = gic_data.redist_regions[i].redist_base; > struct resource *res = &gic_data.redist_regions[i].res; > - u64 typer; > + void __iomem *ptr, *base; > + u64 typer, size, stride; > u32 reg; > > + ptr = base = gic_data.redist_regions[i].redist_base; > + size = resource_size(res); > + > + stride = gic_data.redist_stride ?: SZ_64K * 2; > + if (ptr + stride > base + size) { > + pr_warn("Insufficient size for redistributor region @%llx. Skipping\n", > + res->start); > + continue; > + } > + > reg = readl_relaxed(ptr + GICR_PIDR2) & GIC_PIDR2_ARCH_MASK; > if (reg != GIC_PIDR2_ARCH_GICv3 && > reg != GIC_PIDR2_ARCH_GICv4) { /* We're in trouble... */ > @@ -442,7 +452,28 @@ static int gic_iterate_rdists(int (*fn)(struct redist_region *, void __iomem *)) > } > > do { > + /* > + * We can access GICR_TYPER as we have already > + * checked that we have atleast 128kB or > + * redist_stride > + */ > typer = gic_read_typer(ptr + GICR_TYPER); > + if (!gic_data.redist_stride && > + (typer & GICR_TYPER_VLPIS)) { > + /* VLPI_base + reserved page */ > + stride += SZ_64K * 2; > + > + /* > + * We are larger than we thought, do > + * we still fit? > + */ > + if (ptr + stride > base + size) { > + pr_warn("No last record found in redistributor region @%llx\n", > + gic_data.redist_regions[i].res.start); > + break; > + } > + } > + > ret = fn(gic_data.redist_regions + i, ptr); > if (!ret) > return 0; > @@ -450,12 +481,13 @@ static int gic_iterate_rdists(int (*fn)(struct redist_region *, void __iomem *)) > if (gic_data.redist_regions[i].single_redist) > break; > > - if (gic_data.redist_stride) { > - ptr += gic_data.redist_stride; > - } else { > - ptr += SZ_64K * 2; /* Skip RD_base + SGI_base */ > - if (typer & GICR_TYPER_VLPIS) > - ptr += SZ_64K * 2; /* Skip VLPI_base + reserved page */ > + ptr += stride; > + > + stride = gic_data.redist_stride ?: SZ_64K * 2; > + if (ptr + stride > base + size) { > + pr_warn("No last record found in redistributor region @%llx\n", > + gic_data.redist_regions[i].res.start); > + break; > } > } while (!(typer & GICR_TYPER_LAST)); > } >