Re: [PATCH 1/2] firmware/efi: Tell memblock about EFI reservations
From: Moritz Fischer <mdf@kernel.org>
Date: 2021-05-03 18:59:18
Also in:
kexec
Marc, On Thu, Apr 29, 2021 at 02:35:32PM +0100, Marc Zyngier wrote:
kexec_load_file() relies on the memblock infrastructure to avoid stamping over regions of memory that are essential to the survival of the system. However, nobody seems to agree how to flag these regions as reserved, and (for example) EFI only publishes its reservations in /proc/iomem for the benefit of the traditional, userspace based kexec tool. On arm64 platforms with GICv3, this can result in the payload being placed at the location of the LPI tables. Shock, horror! Let's augment the EFI reservation code with a memblock_reserve() call, protecting our dear tables from the secondary kernel invasion. At some point, someone will have to go and figure out a way to unify these multiple reservation trees, because sprinkling random reservation calls is only a temporary workaround.
Feel free to add (and/or): Reported-by: Moritz Fischer <mdf@kernel.org> Tested-by: Moritz Fischer <mdf@kernel.org>
quoted hunk ↗ jump to hunk
Signed-off-by: Marc Zyngier <maz@kernel.org> --- drivers/firmware/efi/efi.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-)diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 4b7ee3fa9224..026b02f5f7d8 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c@@ -896,11 +896,25 @@ static int __init efi_memreserve_map_root(void) static int efi_mem_reserve_iomem(phys_addr_t addr, u64 size) { struct resource *res, *parent; + int ret; res = kzalloc(sizeof(struct resource), GFP_ATOMIC); if (!res) return -ENOMEM; + /* + * Given that efi_mem_reserve_iomem() can be called at any + * time, only call memblock_reserve() if the architecture + * keeps the infrastructure around. + */ + if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) { + ret = memblock_reserve(addr, size); + if (ret) { + kfree(res); + return ret; + } + } + res->name = "reserved"; res->flags = IORESOURCE_MEM; res->start = addr;@@ -908,7 +922,14 @@ static int efi_mem_reserve_iomem(phys_addr_t addr, u64 size) /* we expect a conflict with a 'System RAM' region */ parent = request_resource_conflict(&iomem_resource, res); - return parent ? request_resource(parent, res) : 0; + ret = parent ? request_resource(parent, res) : 0; + if (ret) { + kfree(res); + if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) + memblock_free(addr, size); + } + + return ret; } int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)-- 2.29.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Thanks, Moritz _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel