Hi Stefano,
On 03/30/2017 11:35 PM, Stefano Stabellini wrote:
parse_vwfi runs after init_traps on cpu0, potentially resulting in the
wrong HCR_EL2 for it. Secondary cpus boot after parse_vwfi, so in their
case init_traps will write the correct set of flags to HCR_EL2.
For cpu0, fix the issue by changing HCR_EL2 setting directly in
parse_vwfi.
Signed-off-by: Stefano Stabellini <sstabell...@kernel.org>
---
This patch should be apply to 4.8, 4.7, 4.6, not to unstable (it will be
fixed differently there).
---
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 614501f..94d2e8a 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -112,6 +112,16 @@ static void __init parse_vwfi(const char *s)
vwfi = NATIVE;
else
vwfi = TRAP;
+ /*
+ * HCR_EL2 has already been set on cpu0, change the setting here, if
+ * needed. Other cpus haven't booted yet, init_traps will setup
+ * HCR_EL2 correctly.
+ */
+ if (vwfi == NATIVE) {
Coding style:
if ( ... )
{
+ register_t hcr;
+ hcr = READ_SYSREG(HCR_EL2);
+ WRITE_SYSREG(hcr & ~(HCR_TWI|HCR_TWE), HCR_EL2);
You are assuming the default value of vwfi and it makes very complicate
for someone to follow the code and modify it.
IHMO, a parsing function should only parse the command line and setup
variable. Hardware configuration or initialization should be done
separately (such as in an init call).
Cheers,
--
Julien Grall
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