# RE: \[PATCH V3 03/13\] x86/HV: Add new hvcall guest address host visibility support

- From: Michael Kelley \<hidden\>
- Date: 2021-08-12 21:10:20 
- List: linux-hyperv
- Page: https://ratatoskr.run/linux-hyperv/2021/08/1476483
- Thread: https://ratatoskr.run/xen-devel/2021/08/1472230/t.md

```text
From: Tianyu Lan <redacted> Sent: Monday, August 9, 2021 10:56 AM

[snip]

> diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
> index ad8a5c586a35..1e4a0882820a 100644
> --- a/arch/x86/mm/pat/set_memory.c
> +++ b/arch/x86/mm/pat/set_memory.c
> @@ -29,6 +29,8 @@
>  #include <asm/proto.h>
>  #include <asm/memtype.h>
>  #include <asm/set_memory.h>
> +#include <asm/hyperv-tlfs.h>
> +#include <asm/mshyperv.h>
> 
>  #include "../mm_internal.h"
> 
> @@ -1980,15 +1982,11 @@ int set_memory_global(unsigned long addr, int numpages)
>  				    __pgprot(_PAGE_GLOBAL), 0);
>  }
> 
> -static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
> +static int __set_memory_enc_pgtable(unsigned long addr, int numpages, bool enc)
>  {
>  	struct cpa_data cpa;
>  	int ret;
> 
> -	/* Nothing to do if memory encryption is not active */
> -	if (!mem_encrypt_active())
> -		return 0;
> -
>  	/* Should not be working on unaligned addresses */
>  	if (WARN_ONCE(addr & ~PAGE_MASK, "misaligned address: %#lx\n", addr))
>  		addr &= PAGE_MASK;
> @@ -2023,6 +2021,17 @@ static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
>  	return ret;
>  }
> 
> +static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
> +{
> +	if (hv_is_isolation_supported())
> +		return hv_set_mem_host_visibility(addr, numpages, !enc);
> +
> +	if (mem_encrypt_active())
> +		return __set_memory_enc_pgtable(addr, numpages, enc);
> +
> +	return 0;
> +}
> +

FYI, this not-yet-accepted patch
https://lore.kernel.org/lkml/ab5a7a983a943e7ca0a7ad28275a2d094c62c371.1623421410.git.ashish.kalra@amd.com/
looks to be providing a generic hook to notify the hypervisor when the
encryption status of a memory range changes.

Michael
```