linux-kernel - [PATCH] RISC-V: mm: Fix set_satp_mode() for platform not having Sv57

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Date:   Tue, 12 Apr 2022 09:03:35 +0530
From:   Anup Patel <apatel@...tanamicro.com>
To:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>
Cc:     Alexandre Ghiti <alexandre.ghiti@...onical.com>,
        Atish Patra <atishp@...shpatra.org>,
        Alistair Francis <Alistair.Francis@....com>,
        Anup Patel <anup@...infault.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Anup Patel <apatel@...tanamicro.com>,
        Mayuresh Chitale <mchitale@...tanamicro.com>
Subject: [PATCH] RISC-V: mm: Fix set_satp_mode() for platform not having Sv57

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")
Reported-by: Mayuresh Chitale <mchitale@...tanamicro.com>
Signed-off-by: Anup Patel <apatel@...tanamicro.com>
---
 arch/riscv/mm/init.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 9535bea8688c..b0793dc0c291 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -718,6 +718,7 @@ static __init void set_satp_mode(void)
 		if (!check_l4) {
 			disable_pgtable_l5();
 			check_l4 = true;
+			memset(early_pg_dir, 0, PAGE_SIZE);
 			goto retry;
 		}
 		disable_pgtable_l4();
-- 
2.25.1