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Date: Tue, 20 Jul 2021 13:50:37 +0200
From: Joerg Roedel <jroedel@suse.de>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>, David Rientjes <rientjes@google.com>,
	Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
	Sean Christopherson <seanjc@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Jon Grimm <jon.grimm@amd.com>, Thomas Gleixner <tglx@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Paolo Bonzini <pbonzini@redhat.com>, Ingo Molnar <mingo@redhat.com>,
	"Kaplan, David" <David.Kaplan@amd.com>,
	Varad Gautam <varad.gautam@suse.com>,
	Dario Faggioli <dfaggioli@suse.com>, x86@kernel.org,
	linux-mm@kvack.org, linux-coco@lists.linux.dev
Subject: Re: Runtime Memory Validation in Intel-TDX and AMD-SNP
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 <4e33d22e-330f-c5ba-bc15-08a3298598c5@linux.intel.com>
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 <YPaYiW/TlrDydY6m@work-vm>
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In-Reply-To: <YPaYiW/TlrDydY6m@work-vm>

On Tue, Jul 20, 2021 at 10:34:01AM +0100, Dr. David Alan Gilbert wrote:
>   Does the bitmap need to be page granulairty or can we work
> on bigger chunks?

I think page granularity is needed, because some regions shared with the
HV are only one page in size (the GHCBs in SEV-ES for example).

But in general it is worth to discuss whether validating memory in
bigger chunks than a page is beneficial wrt. to allocation latency vs.
required HV round-trips for validation.

Regards,

	Joerg