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SubjectRe: [PATCH] RISC-V: mm: Fix set_satp_mode() for platform not having Sv57
Hi Anup,

>
> When Sv57 is not available the satp.MODE test in set_satp_mode() will
> fail and lead to pgdir re-programming for Sv48. The pgdir re-programming
> will fail as well due to pre-existing pgdir entry used for Sv57 and as
> a result kernel fails to boot on RISC-V platform not having Sv57.
>
> To fix above issue, we should clear the pgdir memory in set_satp_mode()
> before re-programming.
>
> Fixes: 011f09d12052 ("riscv: mm: Set sv57 on defaultly")
&gt; Reported-by: Mayuresh Chitale <mchitale@ventanamicro.com>
&gt; Signed-off-by: Anup Patel <apatel@ventanamicro.com>
&gt; ---
&gt; arch/riscv/mm/init.c | 1 +
&gt; 1 file changed, 1 insertion(+)
&gt;
&gt; diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
&gt; index 9535bea8688c..b0793dc0c291 100644
&gt; --- a/arch/riscv/mm/init.c
&gt; +++ b/arch/riscv/mm/init.c
&gt; @@ -718,6 +718,7 @@ static __init void set_satp_mode(void)
&gt; if (!check_l4) {
&gt; disable_pgtable_l5();
&gt; check_l4 = true;
&gt; + memset(early_pg_dir, 0, PAGE_SIZE);
&gt; goto retry;
&gt; }
&gt; disable_pgtable_l4();
&gt; --


I find it that the set_satp_mode function is in .init.text section which begins at 0x80800000.
And its pgd_index in both Sv48 and Sv57 will be 0. So it may not be necessary to clear the
early_pg_dir when the kernel find Sv57 is not supported? And may I get the steps of reproduction
from you?

Yours,
Qinglin
</apatel@ventanamicro.com></mchitale@ventanamicro.com>
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