[PATCH 4/8] lib: sbi_hart: reset sstateen and hstateen

From: "Radim Krčmář" <rkrcmar@ventanamicro.com>
To: opensbi@lists.infradead.org
Subject: [PATCH 4/8] lib: sbi_hart: reset sstateen and hstateen
Date: Tue, 15 Apr 2025 15:19:05 +0200	[thread overview]
Message-ID: <20250415131908.2699782-6-rkrcmar@ventanamicro.com> (raw)
In-Reply-To: <20250415131908.2699782-2-rkrcmar@ventanamicro.com>

Not resetting sstateen is a potential security hole, because U might be
able to access state that S does not properly context-switch.
Similar for hstateen with VS and HS.

Signed-off-by: Radim Krčmář <rkrcmar@ventanamicro.com>
---
 lib/sbi/sbi_hart.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c
index b66b89f6bc51..c280c0b3e85e 100644
--- a/lib/sbi/sbi_hart.c
+++ b/lib/sbi/sbi_hart.c
@@ -111,6 +111,12 @@ static void mstatus_init(struct sbi_scratch *scratch)
 			mstateen_val &= ~SMSTATEEN0_CTR;
 
 		csr_write64(CSR_MSTATEEN0, mstateen_val);
+
+		if (misa_extension('S'))
+			csr_write(CSR_SSTATEEN0, 0);
+
+		if (misa_extension('H'))
+			csr_write64(CSR_HSTATEEN0, (uint64_t)0);
 	}
 
 	if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_12) {
-- 
2.48.1


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