Messages in this thread | | | Date | Tue, 21 May 2013 09:34:22 -0700 | From | David Daney <> | Subject | Re: [PATCH v3 5/5] mips/kvm: Fix ABI by moving manipulation of CP0 registers to KVM_{G,S}ET_MSRS |
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On 05/21/2013 09:28 AM, Gleb Natapov wrote: > On Tue, May 21, 2013 at 09:21:06AM -0700, David Daney wrote: >> On 05/21/2013 08:37 AM, Gleb Natapov wrote: >>> On Mon, May 20, 2013 at 02:01:26PM -0700, David Daney wrote: >>>> From: David Daney <david.daney@cavium.com> >>>> >>>> Because not all 256 CP0 registers are ever implemented, we need a >>>> different method of manipulating them. Use the >>>> KVM_GET_MSRS/KVM_SET_MSRS mechanism as x86 does for its MSRs. >>>> >>> Have you looked at KVM_(GET|SET)_ONE_REG interface (not used by x86, but is >>> used bu arm/ppc/s390). It looks like it is more suitable for your case. >>> Actually you can use it instead of KVM_(GET|SET)_REGS for all registers. >> >> Yes, I suppose it could be used. One problem it has is that there >> is no way to query the set of supported registers. > KVM_GET_REG_LIST
OK, I guess we can switch to KVM_GET_REG_LIST/KVM_(GET|SET)_ONE_REG.
I will revise this patch.
Thanks.
> >> Also you have to >> make multiple calls to set multiple registers, which involves >> vcpu_{load,put} for each register. >> > How often this happens on the fast path on mips?
Rarely, if ever once, the VCPU is running.
Only when initializing the VCPU do we need to set a bunch of registers.
> On x86 this never > happens on the fast path so it uses KVM_(GET|SET)_REGS mostly for > historical reasons. > >> We will definitely implement it for all the FP and General Purpose >> registers. >> >>> >>>> Code related to implementing KVM_GET_MSRS/KVM_SET_MSRS is consolidated >> > > -- > Gleb. >
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