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
