linux-kernel - Re: [PATCH v4 1/3] x86/hyperv: Use slow_virt_to_phys() in page transition hypervisor callback

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Date: Tue, 16 Jan 2024 09:02:29 -0800
From: "rick.p.edgecombe@...ux.intel.com" <rick.p.edgecombe@...ux.intel.com>
To: mhklinux@...look.com, tglx@...utronix.de, mingo@...hat.com,
 bp@...en8.de,  dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com, 
 kirill.shutemov@...ux.intel.com, haiyangz@...rosoft.com,
 wei.liu@...nel.org,  decui@...rosoft.com, luto@...nel.org,
 peterz@...radead.org,  akpm@...ux-foundation.org, urezki@...il.com,
 hch@...radead.org, lstoakes@...il.com,  thomas.lendacky@....com,
 ardb@...nel.org, jroedel@...e.de, seanjc@...gle.com, 
 sathyanarayanan.kuppuswamy@...ux.intel.com, linux-kernel@...r.kernel.org, 
 linux-coco@...ts.linux.dev, linux-hyperv@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v4 1/3] x86/hyperv: Use slow_virt_to_phys() in page
 transition hypervisor callback

On Mon, 2024-01-15 at 18:20 -0800, mhkelley58@...il.com wrote:
> From: Michael Kelley <mhklinux@...look.com>
> 
> In preparation for temporarily marking pages not present during a
> transition between encrypted and decrypted, use slow_virt_to_phys()
> in the hypervisor callback. As long as the PFN is correct,
> slow_virt_to_phys() works even if the leaf PTE is not present.
> The existing functions that depend on vmalloc_to_page() all
> require that the leaf PTE be marked present, so they don't work.
> 
> Update the comments for slow_virt_to_phys() to note this broader
> usage
> and the requirement to work even if the PTE is not marked present.
> 
> Signed-off-by: Michael Kelley <mhklinux@...look.com>

Reviewed-by: Rick Edgecombe <rick.p.edgecombe@...el.com>