> From: Dave Hansen <dave.hansen@xxxxxxxxx>
> Sent: Monday, November 21, 2022 1:01 PM
> [...]
> On 11/21/22 11:51, Dexuan Cui wrote:
> > -static bool tdx_enc_status_changed(unsigned long vaddr, int numpages,
> bool enc)
> > +static bool tdx_enc_status_changed_for_contiguous_pages(unsigned long
> vaddr,
> > + int numpages, bool enc)
>
> That naming is unfortunate.
>
> First, it's getting way too long.
>
> Second, you don't need two of these functions because it's contiguous or
> not. It's because tdx_enc_status_changed() only works on the direct map.
Will try to make one function with better naming.
> > +static bool tdx_enc_status_changed_for_vmalloc(unsigned long vaddr,
> > + int numpages, bool enc)
> > +{
> > + void *start_va = (void *)vaddr;
> > + void *end_va = start_va + numpages * PAGE_SIZE;
> > + phys_addr_t pa;
> > +
> > + if (offset_in_page(vaddr) != 0)
> > + return false;
> > +
> > + while (start_va < end_va) {
> > + pa = slow_virt_to_phys(start_va);
> > + if (!enc)
> > + pa |= cc_mkdec(0);
> > +
> > + if (!tdx_map_gpa(pa, pa + PAGE_SIZE, enc))
> > + return false;
> > +
> > + /*
> > + * private->shared conversion requires only MapGPA call.
> > + *
> > + * For shared->private conversion, accept the page using
> > + * TDX_ACCEPT_PAGE TDX module call.
> > + */
> > + if (enc && !try_accept_one(&pa, PAGE_SIZE, PG_LEVEL_4K))
> > + return false;
>
> Don't we support large vmalloc() mappings these days?
I just noticed Nicholas Piggin's huge vmalloc mapping patches that were
merged in April 2021. I'll take a look and see what I can use here.
> > + start_va += PAGE_SIZE;
> > + }
> > +
> > + return true;
> > +}
>
> I really don't like the copy-and-paste fork here.
>
> I'd almost just rather have this *one* "vmalloc" copy that does
> slow_virt_to_phys() on direct map addresses than have two copies.
It looks like typically set_memory_{de/en}crypted() are not invoked
frequently when Linux is running, e.g. the swiotlb bounce buffers are
only initialzed once with set_memory_decrypt(). A driver runs in a guest
on a hypervisor typically also only initializes the buffers (which need to
be shared with the hypervisor) with set_memory_decrypt() once when
the driver initializes the device. So, it looks like slow_virt_to_phys() may be
acceptable for configuous memory pages as well.
> Can you please look into making *one* function that works on either kind
> of mapping?
Ok. Looking into this using slow_virt_to_phys() for direct map
addresses as well.
