Re: [PATCH 3/5] hyperv/IOMMU: Enable swiotlb bounce buffer for Isolation VM

[Borislav Petkov <bp@xxxxxxxxx>]

On Tue, Nov 16, 2021 at 10:39:21AM -0500, Tianyu Lan wrote:
> diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> index 35487305d8af..65bc385ae07a 100644
> --- a/arch/x86/mm/mem_encrypt.c
> +++ b/arch/x86/mm/mem_encrypt.c
> @@ -31,6 +31,7 @@
>  #include <asm/processor-flags.h>
>  #include <asm/msr.h>
>  #include <asm/cmdline.h>
> +#include <asm/mshyperv.h>
>  
>  #include "mm_internal.h"
>  
> @@ -203,7 +204,8 @@ void __init sev_setup_arch(void)
>       phys_addr_t total_mem = memblock_phys_mem_size();
>       unsigned long size;
>  
> -     if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
> +     if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT)
> +         && !hv_is_isolation_supported())

Are we gonna start sprinkling this hv_is_isolation_supported() check
everywhere now?

Are those isolation VMs SEV-like guests? Is CC_ATTR_GUEST_MEM_ENCRYPT
set on them?

What you should do, instead, is add an isol. VM specific
hv_cc_platform_has() just like amd_cc_platform_has() and handle
the cc_attrs there for your platform, like return false for
CC_ATTR_GUEST_MEM_ENCRYPT and then you won't need to add that hv_* thing
everywhere.

And then fix it up in __set_memory_enc_dec() too.

-- 
Regards/Gruss,
    Boris.

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