Re: [PATCH V5 09/12] x86/Swiotlb: Add Swiotlb bounce buffer remap function for HV IVM

[Tianyu Lan <ltykernel@xxxxxxxxx>]

On 9/15/2021 11:42 PM, Michael Kelley wrote:
> > @@ -196,13 +199,34 @@ static void swiotlb_init_io_tlb_mem(struct io_tlb_mem *mem, phys_addr_t start,
> >   		mem->slots[i].orig_addr = INVALID_PHYS_ADDR;
> >   		mem->slots[i].alloc_size = 0;
> >   	}
> > +
> > +	if (set_memory_decrypted((unsigned long)vaddr, bytes >> PAGE_SHIFT))
> > +		return -EFAULT;
> > +
> > +	/*
> > +	 * Map memory in the unencrypted physical address space when requested
> > +	 * (e.g. for Hyper-V AMD SEV-SNP Isolation VMs).
> > +	 */
> > +	if (swiotlb_unencrypted_base) {
> > +		phys_addr_t paddr = __pa(vaddr) + swiotlb_unencrypted_base;
> Nit:  Use "start" instead of "__pa(vaddr)" since "start" is already the needed
> physical address.


Yes, "start" should be used here.

> > @@ -304,7 +332,7 @@ int
> >   swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
> >   {
> >   	struct io_tlb_mem *mem = &io_tlb_default_mem;
> > -	unsigned long bytes = nslabs << IO_TLB_SHIFT;
> > +	int ret;
> >
> >   	if (swiotlb_force == SWIOTLB_NO_FORCE)
> >   		return 0;
> > @@ -318,8 +346,9 @@ swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs)
> >   	if (!mem->slots)
> >   		return -ENOMEM;
> >
> > -	set_memory_decrypted((unsigned long)tlb, bytes >> PAGE_SHIFT);
> > -	swiotlb_init_io_tlb_mem(mem, virt_to_phys(tlb), nslabs, true);
> > +	ret = swiotlb_init_io_tlb_mem(mem, virt_to_phys(tlb), nslabs, true);
> > +	if (ret)
> Before returning the error, free the pages obtained from the earlier call
> to __get_free_pages()?

Yes, will fix.

Thanks.