linux-kernel - Re: [PATCH v3] RISC-V: Mark IORESOURCE_EXCLUSIVE for reserved mem instead of IORESOURCE

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Message-ID: <mhng-d1f0bf41-82a3-4e76-98a0-c787ebcd0799@palmer-ri-x1c9>
Date:   Wed, 01 Jun 2022 22:57:22 -0700 (PDT)
From:   Palmer Dabbelt <palmer@...belt.com>
To:     guoren@...nel.org
CC:     mick@....forth.gr, Paul Walmsley <paul.walmsley@...ive.com>,
        aou@...s.berkeley.edu, anup@...infault.org,
        akpm@...ux-foundation.org, wangkefeng.wang@...wei.com,
        rppt@...nel.org, david@...hat.com, wangborong@...rlc.com,
        twd2.me@...il.com, seanjc@...gle.com, alex@...ti.fr,
        petr.pavlu@...e.com, Atish Patra <atishp@...osinc.com>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        jianghuaming.jhm@...baba-inc.com, heiko@...ech.de,
        xianting.tian@...ux.alibaba.com
Subject:     Re: [PATCH v3] RISC-V: Mark IORESOURCE_EXCLUSIVE for reserved mem instead of IORESOURCE_BUSY

On Sun, 29 May 2022 19:47:51 PDT (-0700), guoren@...nel.org wrote:
> Hi Palmer,
>
> Please have a look at this patch which is a critical fixup. Our
> current riscv implementation has broken the reserved memory.

Putting "fix" somewhere in the subject is generally the best way to do 
that, this one just looked like a feature and I stumbled into it when 
going through stuff for this merge window.

It's in for-next, which is still aimed at 5.19.

Thanks!

>
> On Wed, May 18, 2022 at 9:34 AM Xianting Tian
> <xianting.tian@...ux.alibaba.com> wrote:
>>
>> Commit 00ab027a3b82 ("RISC-V: Add kernel image sections to the resource tree")
>> marked IORESOURCE_BUSY for reserved memory, which caused resource map
>> failed in subsequent operations of related driver, so remove the
>> IORESOURCE_BUSY flag. In order to prohibit userland mapping reserved
>> memory, mark IORESOURCE_EXCLUSIVE for it.
>>
>> The code to reproduce the issue,
>> dts:
>>         mem0: memory@...00000 {
>>                 reg = <0x0 0xa0000000 0 0x1000000>;
>>                 no-map;
>>         };
>>
>>         &test {
>>                 status = "okay";
>>                 memory-region = <&mem0>;
>>         };
>>
>> code:
>>         np = of_parse_phandle(pdev->dev.of_node, "memory-region", 0);
>>         ret = of_address_to_resource(np, 0, &r);
>>         base = devm_ioremap_resource(&pdev->dev, &r);
>>         // base = -EBUSY
>>
>> Fixes: 00ab027a3b82 ("RISC-V: Add kernel image sections to the resource tree")
>> Reported-by: Huaming Jiang <jianghuaming.jhm@...baba-inc.com>
>> Reviewed-by: Guo Ren <guoren@...nel.org>
>> Reviewed-by: Heiko Stuebner <heiko@...ech.de>
>> Tested-by: Heiko Stuebner <heiko@...ech.de>
>> Co-developed-by: Nick Kossifidis <mick@....forth.gr>
>> Signed-off-by: Xianting Tian <xianting.tian@...ux.alibaba.com>
>> ---
>> Changes from v2:
>> - Fix typo in commit message: casued -> caused
>> - Remove Reviewed-by of Nick Kossifidis, who didn't give Reviewed-by actually
>> - Add Co-developed-by of Nick
>>
>> Changes from v1:
>> - Mark reserved memory as IORESOURCE_EXCLUSIVE, suggested by Nick
>> ---
>>  arch/riscv/kernel/setup.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
>> index 834eb652a7b9..e0a00739bd13 100644
>> --- a/arch/riscv/kernel/setup.c
>> +++ b/arch/riscv/kernel/setup.c
>> @@ -189,7 +189,7 @@ static void __init init_resources(void)
>>                 res = &mem_res[res_idx--];
>>
>>                 res->name = "Reserved";
>> -               res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
>> +               res->flags = IORESOURCE_MEM | IORESOURCE_EXCLUSIVE;
>>                 res->start = __pfn_to_phys(memblock_region_reserved_base_pfn(region));
>>                 res->end = __pfn_to_phys(memblock_region_reserved_end_pfn(region)) - 1;
>>
>> @@ -214,7 +214,7 @@ static void __init init_resources(void)
>>
>>                 if (unlikely(memblock_is_nomap(region))) {
>>                         res->name = "Reserved";
>> -                       res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
>> +                       res->flags = IORESOURCE_MEM | IORESOURCE_EXCLUSIVE;
>>                 } else {
>>                         res->name = "System RAM";
>>                         res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
>> --
>> 2.17.1
>>