[PULL v2 12/12] hvf: arm: Ignore cache operations on MMIO

[Richard Henderson <richard.henderson@linaro.org>]

From: Alexander Graf <agraf@csgraf.de>

Apple's Hypervisor.Framework forwards cache operations as MMIO traps
into user space. For MMIO however, these have no meaning: There is no
cache attached to them.

So let's just treat cache data exits as nops.

This fixes OpenBSD booting as guest.

Reported-by: AJ Barris <AwlsomeAlex@github.com>
Signed-off-by: Alexander Graf <agraf@csgraf.de>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Mark Kettenis <kettenis@openbsd.org>
Reference: https://github.com/utmapp/UTM/issues/3197
Message-Id: <20211026071241.74889-1-agraf@csgraf.de>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/arm/hvf/hvf.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/target/arm/hvf/hvf.c b/target/arm/hvf/hvf.c
index bff3e0cde7..0dc96560d3 100644
--- a/target/arm/hvf/hvf.c
+++ b/target/arm/hvf/hvf.c
@@ -1150,12 +1150,19 @@ int hvf_vcpu_exec(CPUState *cpu)
         uint32_t sas = (syndrome >> 22) & 3;
         uint32_t len = 1 << sas;
         uint32_t srt = (syndrome >> 16) & 0x1f;
+        uint32_t cm = (syndrome >> 8) & 0x1;
         uint64_t val = 0;
 
         trace_hvf_data_abort(env->pc, hvf_exit->exception.virtual_address,
                              hvf_exit->exception.physical_address, isv,
                              iswrite, s1ptw, len, srt);
 
+        if (cm) {
+            /* We don't cache MMIO regions */
+            advance_pc = true;
+            break;
+        }
+
         assert(isv);
 
         if (iswrite) {
-- 
2.25.1