From: Moritz Fischer <mdf@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
James Morse <james.morse@arm.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Hanjun Guo <guohanjun@huawei.com>,
Sudeep Holla <sudeep.holla@arm.com>,
Eric Biederman <ebiederm@xmission.com>,
Bhupesh Sharma <bhsharma@redhat.com>,
AKASHI Takahiro <takahiro.akashi@linaro.org>,
kernel-team@android.com
Subject: Re: [PATCH 1/2] firmware/efi: Tell memblock about EFI reservations
Date: Mon, 3 May 2021 11:56:36 -0700 [thread overview]
Message-ID: <YJBHZFMhBL4z0445@epycbox.lan> (raw)
In-Reply-To: <20210429133533.1750721-2-maz@kernel.org>
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>
> 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
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next prev parent reply other threads:[~2021-05-03 18:59 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 13:35 [PATCH 0/2] arm64: kexec_file_load vs memory reservations Marc Zyngier
2021-04-29 13:35 ` [PATCH 1/2] firmware/efi: Tell memblock about EFI reservations Marc Zyngier
2021-05-03 18:56 ` Moritz Fischer [this message]
2021-05-13 3:20 ` Dave Young
2021-05-13 11:11 ` Marc Zyngier
2021-04-29 13:35 ` [PATCH 2/2] ACPI: arm64: Reserve the ACPI tables in memblock Marc Zyngier
2021-05-03 18:57 ` Moritz Fischer
2021-05-12 18:04 ` [PATCH 0/2] arm64: kexec_file_load vs memory reservations Marc Zyngier
2021-05-13 3:17 ` Dave Young
2021-05-13 11:07 ` Marc Zyngier
2021-05-18 11:48 ` Will Deacon
2021-05-18 14:23 ` Bhupesh Sharma
2021-05-19 15:19 ` Catalin Marinas
2021-05-25 16:22 ` Marc Zyngier
2021-06-02 14:22 ` James Morse
2021-06-02 15:59 ` Marc Zyngier
2021-06-02 16:58 ` James Morse
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