Message-ID: <8670a645-f48f-1d64-e5a5-291f2593643a@suse.cz>
Date:   Fri, 3 Mar 2023 15:05:09 +0100
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Subject: Re: [PATCH RFC v8 09/56] KVM: SEV: Handle memory backed by restricted
 memfd
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To:     Michael Roth <michael.roth@amd.com>, kvm@vger.kernel.org
Cc:     linux-coco@lists.linux.dev, linux-mm@kvack.org,
        linux-crypto@vger.kernel.org, x86@kernel.org,
        linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
        jroedel@suse.de, thomas.lendacky@amd.com, hpa@zytor.com,
        ardb@kernel.org, pbonzini@redhat.com, seanjc@google.com,
        vkuznets@redhat.com, jmattson@google.com, luto@kernel.org,
        dave.hansen@linux.intel.com, slp@redhat.com, pgonda@google.com,
        peterz@infradead.org, srinivas.pandruvada@linux.intel.com,
        rientjes@google.com, dovmurik@linux.ibm.com, tobin@ibm.com,
        bp@alien8.de, kirill@shutemov.name, ak@linux.intel.com,
        tony.luck@intel.com, marcorr@google.com,
        sathyanarayanan.kuppuswamy@linux.intel.com, alpergun@google.com,
        dgilbert@redhat.com, jarkko@kernel.org, ashish.kalra@amd.com,
        nikunj.dadhania@amd.com, Nikunj A Dadhania <nikunj@amd.com>
References: <20230220183847.59159-1-michael.roth@amd.com>
 <20230220183847.59159-10-michael.roth@amd.com>
From:   Vlastimil Babka <vbabka@suse.cz>
In-Reply-To: <20230220183847.59159-10-michael.roth@amd.com>
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On 2/20/23 19:38, Michael Roth wrote:
> From: Nikunj A Dadhania <nikunj@amd.com>
> 
> Do not pin the guest memory backed by a restrictedmem backend, as
> pages in the restrictedmem are already pinned. Instead, populate the
> pages array for these guests using the already-pinned pages provided by

IIUC the "already pinned" became "effectively unmovable and unevictable"
since the earlier versions, so that would be more accurate now?

> +static int sev_private_mem_get_pages(struct kvm *kvm, unsigned long addr,
> +				     unsigned long size, unsigned long npages,
> +				     struct page **pages)
> +{
> +	return kvm_vm_do_hva_range_op(kvm, addr, addr + size,
> +				      sev_private_mem_get_pages_handler, pages);
> +}
> +
>  /*
>   * Legacy SEV guest pin the pages and return the array populated with pinned
>   * pages.
> + *
> + * SEV guests using restricted memfd backend, pages are already marked as
> + * unmovable and unevictable. Populate the pages array for these guests using
> + * restrictedmem get_pfn.

Right.