From: kirill.shutemov@xxxxxxxxxxxxxxx <kirill.shutemov@xxxxxxxxxxxxxxx> Sent: Monday, January 8, 2024 5:08 AM
>
> On Fri, Jan 05, 2024 at 10:30:23AM -0800, mhkelley58@xxxxxxxxx wrote:
> > From: Michael Kelley <mhklinux@xxxxxxxxxxx>
> >
> > In preparation for temporarily marking pages not present during a
> > transition between encrypted and decrypted, use slow_virt_to_phys()
> > in the hypervisor callback. As long as the PFN is correct,
> > slow_virt_to_phys() works even if the leaf PTE is not present.
> > The existing functions that depend on vmalloc_to_page() all
> > require that the leaf PTE be marked present, so they don't work.
> >
> > Update the comments for slow_virt_to_phys() to note this broader usage
> > and the requirement to work even if the PTE is not marked present.
> >
> > Signed-off-by: Michael Kelley <mhklinux@xxxxxxxxxxx>
> > ---
> > arch/x86/hyperv/ivm.c | 9 ++++++++-
> > arch/x86/mm/pat/set_memory.c | 13 +++++++++----
> > 2 files changed, 17 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
> > index 02e55237d919..8ba18635e338 100644
> > --- a/arch/x86/hyperv/ivm.c
> > +++ b/arch/x86/hyperv/ivm.c
> > @@ -524,7 +524,14 @@ static bool hv_vtom_set_host_visibility(unsigned
> long kbuffer, int pagecount, bo
> > return false;
> >
> > for (i = 0, pfn = 0; i < pagecount; i++) {
> > - pfn_array[pfn] = virt_to_hvpfn((void *)kbuffer + i * HV_HYP_PAGE_SIZE);
> > + /*
> > + * Use slow_virt_to_phys() because the PRESENT bit has been
> > + * temporarily cleared in the PTEs. slow_virt_to_phys() works
> > + * without the PRESENT bit while virt_to_hvpfn() or similar
> > + * does not.
> > + */
> > + pfn_array[pfn] = slow_virt_to_phys((void *)kbuffer +
> > + i * HV_HYP_PAGE_SIZE) >> HV_HYP_PAGE_SHIFT;
>
> I think you can make it much more readable by introducing few variables:
>
> virt = (void *)kbuffer + i * HV_HYPPAGE_SIZE;
> phys = slow_virt_to_phys(virt);
> pfn_array[pfn] = phys >> HV_HYP_PAGE_SHIFT;
>
Agreed. I'll do this in the next version.
Michael
