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lib: sbi_hart: reset hstatus

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hstatus.HU must be cleared, because U-mode could otherwise use the
HLS/HSV instructions.  This would allow U-mode to read physical memory
directly if vgatp and vsatp was 0.

The remaining fields don't seem like a security vulnerability now, but
clearing the whole CSR is not an issue, so do that be safe.

Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Radim Krčmář <rkrcmar@ventanamicro.com>
Link: https://lore.kernel.org/r/20250429142549.3673976-5-rkrcmar@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Radim Krčmář
2025-04-29 16:25:45 +02:00
committed by Anup Patel
parent 65e8be4fe8
commit 009f77a9f0
1 changed files with 3 additions and 0 deletions
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3
lib/sbi/sbi_hart.c
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@@ -85,6 +85,9 @@ static void mstatus_init(struct sbi_scratch *scratch)
#endif
}
if (misa_extension('H'))
csr_write(CSR_HSTATUS, 0);
if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SMSTATEEN)) {
mstateen_val = csr_read64(CSR_MSTATEEN0);
mstateen_val |= SMSTATEEN_STATEN;