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Re: [Qemu-devel] [PATCH] spapr: Don't set the TM ibm, pa-features bit in
Re: [Qemu-devel] [PATCH] spapr: Don't set the TM ibm, pa-features bit in PR KVM mode
Tue, 5 Apr 2016 17:33:27 +1000
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On 04/05/2016 02:09 PM, David Gibson wrote:
On Tue, Apr 05, 2016 at 12:12:01PM +1000, Paul Mackerras wrote:
On Mon, Apr 04, 2016 at 09:09:28PM +1000, Anton Blanchard wrote:
We don't support transactional memory in PR KVM, so don't tell
the OS that we do.
This assumes PR KVM won't ever support TM, which is hopefully not
true. If PR KVM does get TM support in future, then QEMU will have no
clear way to know whether it needs to clear the pa-features bit or
not. I think we need to define some way for the KVM implementation to
tell qemu which of these kinds of CPU features it supports.
Yeah, I think we need some sort of capability flag for this. We also
need to isolate this KVM capability testing better into the KVM code,
so we won't break things on TCG.
Speaking of which... I don't imagine we implement TM instructions in
TCG either, so we should probably make sure TM isn't advertised there
TM is "supported" in TCG:
56a846157 "target-ppc: Introduce TM Noops"
Add degenerate implementations of the non-privileged Transactional
Memory instructions tend., tabort*. and tsr. This implementation
simply checks the MSR[TM] bit and then sets CR0 to 0b0000. This
is a reasonable degenerate implementation since transactions are
never allowed to begin and hence MSR[TS] is always 0b00.
Signed-off-by: Tom Musta <address@hidden>
Signed-off-by: Alexander Graf <address@hidden>
- Re: [Qemu-devel] PR KVM and TM issues, Anton Blanchard, 2016/04/04
- [Qemu-devel] [PATCH] powerpc: Clear user CPU feature bits if TM is disabled at runtime, Anton Blanchard, 2016/04/04
- [Qemu-devel] [PATCH 1/3] powerpc: scan_features() updates incorrect bits, Anton Blanchard, 2016/04/14
- Re: [Qemu-devel] [1/3] powerpc: scan_features() updates incorrect bits, Michael Ellerman, 2016/04/18
- [Qemu-devel] [PATCH v2 1/3] powerpc: scan_features() updates incorrect bits for REAL_LE, Michael Ellerman, 2016/04/18