Re: [PATCH 09/10] KVM: PPC: Support SC1 hypercalls for PAPR in PR mode

Am 12.08.2011 um 05:33 schrieb David Gibson [off-list ref]:

On Tue, Aug 09, 2011 at 06:31:47PM +0200, Alexander Graf wrote:

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PAPR defines hypercalls as SC1 instructions. Using these, the guest modif=

ies

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page tables and does other privileged operations that it wouldn't be allo=

wed

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to do in supervisor mode.
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This patch adds support for PR KVM to trap these instructions and route t=

hem

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through the same PAPR hypercall interface that we already use for HV styl=

e

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KVM.

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This will work on a powermac or bare metal host.  Unfortunately, it's
not enough on a pSeries LPAR host - the sc 1 instruction from the
guest problem state will go direct to the hypervisor, which will
return an error rather than trapping to the guest kernel.
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The only way around this I can see is for qemu to search for and patch
up sc 1 instructions to something else.  Obviously that would also
need some kernel support, and probably a capability to let it know if
it's necessary.

Well I'd like to keep Qemu out of the patching business, so the guest kernel=
 would have to patch itself. But yes, PHyP guests can't run this target yet :=
). I'll take a stab at that too, but one continent at a time! ;)


Alex

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