Messages in this thread | | | From | Vitaly Kuznetsov <> | Subject | Re: [PATCH v2 6/6] KVM: nVMX: optimize prepare_vmcs02{,_full} for Enlightened VMCS case | Date | Wed, 25 Jul 2018 10:37:43 +0200 |
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Paolo Bonzini <pbonzini@redhat.com> writes:
> On 21/06/2018 14:30, Vitaly Kuznetsov wrote: >> +static __always_inline bool evmcs_needs_write(struct vcpu_vmx *vmx, >> + u16 clean_field) >> +{ >> + if (vmx->nested.dirty_vmcs12) >> + return true; > > Why is this needed? If it weren't for it, you could pass hv_evmcs > directly to evmcs_needs_write, which would simplify the code a bit in > the caller.
This is an equivalent of prepare_vmcs02()/prepare_vmcs02_full() split for eVMCS case: when we switch from L2 guest A to L2 guest B we need to write the whole VMCS so evmcs_needs_write() needs to return true.
We can, however, make an optimisation: forcefuly reset hv_clean_fields mask on enlightened vmptrld making 'dirty_vmcs12' check redundant.
This series was posted quite some time ago, I'll rebase and re-test with the fix included.
Thanks!
-- Vitaly
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