On 21/10/16 09:45, Marc Zyngier wrote:
+Robert
On 21/10/16 08:01, Auger Eric wrote:
Hi,
I am not able to boot 4.9-rc1 as a guest on Cavium ThunderX (dt and acpi
mode). Bisecting the guest shows that the problem shows up at
91ef84428a86b75a52e15c6fe4f56b446ba75f93
irqchip/gic-v3: Reset BPR during initialization
If I remove the write to the ICC_BPR1_EL1 register on guest, the VM boots.
That's very odd. A ICC_BPR1_EL1 access when HCR_EL2.IMO is set only
affects ICH_VMCR_EL2.VBPR1. It is not trapped, since we don't set
ICH_HCR_EL2.TALL1. It is a very boring sysreg!
So from a pure architectural point of view, I don't see how this can
fail. I've just run the same configuration on my Freescale board (GICv3
as well), and can't see any issue at all.
Wow. Of all the patches I written for arm64 this was not the one I
regarded as especially risky [at least when compared to the others ;-)].
Of course it does rely on writing a zero being "an attempt to program
the binary point field to a value less than the reset value" and "sets
the field to the reset value." and from a silicon validation point of
view that might be regarded as a interesting corner case...
Daniel.
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
