linux-kernel - [PATCH v6 1/3] RISC-V: Fix MEMREMAP

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Date:   Mon, 14 Nov 2022 14:35:34 +0530
From:   Anup Patel <apatel@...tanamicro.com>
To:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>
Cc:     Atish Patra <atishp@...shpatra.org>,
        Heiko Stuebner <heiko@...ech.de>,
        Arnd Bergmann <arnd@...db.de>,
        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 v6 1/3] RISC-V: Fix MEMREMAP_WB for systems with Svpbmt

Currently, the memremap() called with MEMREMAP_WB maps memory using
the generic ioremap() function which breaks on system with Svpbmt
because memory mapped using _PAGE_IOREMAP page attributes is treated
as strongly-ordered non-cacheable IO memory.

To address this, we implement RISC-V specific arch_memremap_wb()
which maps memory using _PAGE_KERNEL page attributes resulting in
write-back cacheable mapping on systems with Svpbmt.

Fixes: ff689fd21cb1 ("riscv: add RISC-V Svpbmt extension support")
Co-developed-by: Mayuresh Chitale <mchitale@...tanamicro.com>
Signed-off-by: Mayuresh Chitale <mchitale@...tanamicro.com>
Signed-off-by: Anup Patel <apatel@...tanamicro.com>
---
 arch/riscv/include/asm/io.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
index 92080a227937..42497d487a17 100644
--- a/arch/riscv/include/asm/io.h
+++ b/arch/riscv/include/asm/io.h
@@ -135,4 +135,9 @@ __io_writes_outs(outs, u64, q, __io_pbr(), __io_paw())
 
 #include <asm-generic/io.h>
 
+#ifdef CONFIG_MMU
+#define arch_memremap_wb(addr, size)	\
+	((__force void *)ioremap_prot((addr), (size), _PAGE_KERNEL))
+#endif
+
 #endif /* _ASM_RISCV_IO_H */
-- 
2.34.1