Re: [PATCH 10/13] x86/Swiotlb: Add Swiotlb bounce buffer remap function for HV IVM

[Tianyu Lan <ltykernel@xxxxxxxxx>]

Hi Konrad:
     Thanks for your review.

On 7/30/2021 12:29 AM, Konrad Rzeszutek Wilk wrote:
> > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> > index 1fa81c096c1d..6866e5784b53 100644
> > --- a/kernel/dma/swiotlb.c
> > +++ b/kernel/dma/swiotlb.c
> > @@ -194,8 +194,13 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem 
> > *mem, phys_addr_t start,
> >                 mem->slots[i].alloc_size = 0;
> >         }
> >   
> > -	set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT);
> > -       memset(vaddr, 0, bytes);
> > +       mem->vaddr = dma_map_decrypted(vaddr, bytes);
> > +       if (!mem->vaddr) {
> > +               pr_err("Failed to decrypt memory.\n");
> I am wondering if it would be worth returning an error code in this
> function instead of just printing an error?
Yes, this is good idea and will update in the next version.

> For this patch I think it is Ok, but perhaps going forward this would be
> better done as I am thinking - is there some global guest->hyperv
> reporting mechanism so that if this fails - it ends up being bubbled up
> to the HyperV console-ish?
Hyper-V has such panic page report mechanism. Guest can pass one page 
log to host during crash.