tree b43918e749c182afff936231f0f64b7562adeee4
parent 93cb52b7a3ccc64e8d28813324818edae07e21d5
author Daniel Henrique Barboza <dbarboza@ventanamicro.com> 1713005968 +0300
committer Alistair Francis <alistair.francis@wdc.com> 1717377132 +1000

target/riscv: prioritize pmp errors in raise_mmu_exception()

raise_mmu_exception(), as is today, is prioritizing guest page faults by
checking first if virt_enabled && !first_stage, and then considering the
regular inst/load/store faults.

There's no mention in the spec about guest page fault being a higher
priority that PMP faults. In fact, privileged spec section 3.7.1 says:

"Attempting to fetch an instruction from a PMP region that does not have
execute permissions raises an instruction access-fault exception.
Attempting to execute a load or load-reserved instruction which accesses
a physical address within a PMP region without read permissions raises a
load access-fault exception. Attempting to execute a store,
store-conditional, or AMO instruction which accesses a physical address
within a PMP region without write permissions raises a store
access-fault exception."

So, in fact, we're doing it wrong - PMP faults should always be thrown,
regardless of also being a first or second stage fault.

The way riscv_cpu_tlb_fill() and get_physical_address() work is
adequate: a TRANSLATE_PMP_FAIL error is immediately reported and
reflected in the 'pmp_violation' flag. What we need is to change
raise_mmu_exception() to prioritize it.

Reported-by: Joseph Chan <jchan@ventanamicro.com>
Fixes: 82d53adfbb ("target/riscv/cpu_helper.c: Invalid exception on MMU translation stage")
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20240413105929.7030-1-alexei.filippov@syntacore.com>
Cc: qemu-stable <qemu-stable@nongnu.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>