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[Qemu-riscv] [PATCH 2/2] RISC-V: Only Check PMP if MMU translation succe

From: Hesham Almatary
Subject: [Qemu-riscv] [PATCH 2/2] RISC-V: Only Check PMP if MMU translation succeeds
Date: Sat, 18 May 2019 20:13:23 +0100

The current implementation unnecessarily checks for PMP even if MMU translation
failed. This may trigger a wrong PMP access exception instead of
a page exception.

For example, the very first instruction fetched after the first satp write in
S-Mode will trigger a PMP access fault instead of an instruction fetch page

This patch prioritises MMU exceptions over PMP exceptions and only checks for
PMP if MMU translation succeeds.

Signed-off-by: Hesham Almatary <address@hidden>
 target/riscv/cpu_helper.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index b48de36114..7c7282c680 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -403,6 +403,7 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int 
                   " prot %d\n", __func__, address, ret, pa, prot);

     if (riscv_feature(env, RISCV_FEATURE_PMP) &&
+        (ret == TRANSLATE_SUCCESS) &&
         !pmp_hart_has_privs(env, pa, TARGET_PAGE_SIZE, 1 << access_type)) {
         pmp_violation = true;
         ret = TRANSLATE_FAIL;

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