Re: [PATCH v9 2/8] KVM: arm/arm64: Re-factor setting the Stage 2 entry to exec on fault

[Suzuki K Poulose]

On 03/12/2018 13:32, Anshuman Khandual wrote:
> On 10/31/2018 11:27 PM, Punit Agrawal wrote:
> > Stage 2 fault handler marks a page as executable if it is handling an
> > execution fault or if it was a permission fault in which case the
> > executable bit needs to be preserved.
> >
> > The logic to decide if the page should be marked executable is
> > duplicated for PMD and PTE entries. To avoid creating another copy
> > when support for PUD hugepages is introduced refactor the code to
> > share the checks needed to mark a page table entry as executable.
> >
> > Signed-off-by: Punit Agrawal <punit.agrawal@xxxxxxx>
> > Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> > Cc: Christoffer Dall <christoffer.dall@xxxxxxx>
> > Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
> > ---
> >   virt/kvm/arm/mmu.c | 28 +++++++++++++++-------------
> >   1 file changed, 15 insertions(+), 13 deletions(-)
> >
> > diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
> > index 59595207c5e1..6912529946fb 100644
> > --- a/virt/kvm/arm/mmu.c
> > +++ b/virt/kvm/arm/mmu.c
> > @@ -1475,7 +1475,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
> >   			  unsigned long fault_status)
> >   {
> >   	int ret;
> > -	bool write_fault, exec_fault, writable, force_pte = false;
> > +	bool write_fault, writable, force_pte = false;
> > +	bool exec_fault, needs_exec;
>
> New line not required, still within 80 characters.
>
> >   	unsigned long mmu_seq;
> >   	gfn_t gfn = fault_ipa >> PAGE_SHIFT;
> >   	struct kvm *kvm = vcpu->kvm;
> > @@ -1598,19 +1599,25 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
> >   	if (exec_fault)
> >   		invalidate_icache_guest_page(pfn, vma_pagesize);
> >   
> > +	/*
> > +	 * If we took an execution fault we have made the
> > +	 * icache/dcache coherent above and should now let the s2
>
> Coherent or invalidated with invalidate_icache_guest_page ?

We also do clean_dcache above if needed. So that makes sure
the data is coherent. Am I missing something here ?

> > +	 * mapping be executable.
> > +	 *
> > +	 * Write faults (!exec_fault && FSC_PERM) are orthogonal to
> > +	 * execute permissions, and we preserve whatever we have.
> > +	 */
>
> Otherwise looks good.


Suzuki