Messages in this thread | | | Subject | Re: [PATCH 10/22] kvm: mmu: Add TDP MMU PF handler | From | Paolo Bonzini <> | Date | Wed, 30 Sep 2020 19:37:57 +0200 |
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On 30/09/20 18:37, Sean Christopherson wrote: >> + ret = page_fault_handle_target_level(vcpu, write, map_writable, >> + as_id, &iter, pfn, prefault); >> + >> + /* If emulating, flush this vcpu's TLB. */ > Why? It's obvious _what_ the code is doing, the comment should explain _why_. > >> + if (ret == RET_PF_EMULATE) >> + kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu); >> + >> + return ret; >> +}
In particular it seems to be only needed in this case...
+ /* + * If the page fault was caused by a write but the page is write + * protected, emulation is needed. If the emulation was skipped, + * the vCPU would have the same fault again. + */ + if ((make_spte_ret & SET_SPTE_WRITE_PROTECTED_PT) && write) + ret = RET_PF_EMULATE; +
... corresponding to this code in mmu.c
if (set_spte_ret & SET_SPTE_WRITE_PROTECTED_PT) { if (write_fault) ret = RET_PF_EMULATE; kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); }
So it should indeed be better to make the code in page_fault_handle_target_level look the same as mmu/mmu.c.
Paolo
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