linux-kernel - Re: [PATCH v7 05/12] KVM: guest_memfd: Add flag to remove from direct map

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <yq5ajz07czvz.fsf@kernel.org>
Date: Mon, 03 Nov 2025 13:27:04 +0530
From: Aneesh Kumar K.V <aneesh.kumar@...nel.org>
To: "Roy, Patrick" <roypat@...zon.co.uk>
Cc: "Roy, Patrick" <roypat@...zon.co.uk>,
	"pbonzini@...hat.com" <pbonzini@...hat.com>,
	"corbet@....net" <corbet@....net>,
	"maz@...nel.org" <maz@...nel.org>,
	"oliver.upton@...ux.dev" <oliver.upton@...ux.dev>,
	"joey.gouly@....com" <joey.gouly@....com>,
	"suzuki.poulose@....com" <suzuki.poulose@....com>,
	"yuzenghui@...wei.com" <yuzenghui@...wei.com>,
	"catalin.marinas@....com" <catalin.marinas@....com>,
	"will@...nel.org" <will@...nel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"bp@...en8.de" <bp@...en8.de>,
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
	"x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
	"luto@...nel.org" <luto@...nel.org>,
	"peterz@...radead.org" <peterz@...radead.org>,
	"willy@...radead.org" <willy@...radead.org>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	"david@...hat.com" <david@...hat.com>,
	"lorenzo.stoakes@...cle.com" <lorenzo.stoakes@...cle.com>,
	"Liam.Howlett@...cle.com" <Liam.Howlett@...cle.com>,
	"vbabka@...e.cz" <vbabka@...e.cz>,
	"rppt@...nel.org" <rppt@...nel.org>,
	"surenb@...gle.com" <surenb@...gle.com>,
	"mhocko@...e.com" <mhocko@...e.com>,
	"song@...nel.org" <song@...nel.org>,
	"jolsa@...nel.org" <jolsa@...nel.org>,
	"ast@...nel.org" <ast@...nel.org>,
	"daniel@...earbox.net" <daniel@...earbox.net>,
	"andrii@...nel.org" <andrii@...nel.org>,
	"martin.lau@...ux.dev" <martin.lau@...ux.dev>,
	"eddyz87@...il.com" <eddyz87@...il.com>,
	"yonghong.song@...ux.dev" <yonghong.song@...ux.dev>,
	"john.fastabend@...il.com" <john.fastabend@...il.com>,
	"kpsingh@...nel.org" <kpsingh@...nel.org>,
	"sdf@...ichev.me" <sdf@...ichev.me>,
	"haoluo@...gle.com" <haoluo@...gle.com>,
	"jgg@...pe.ca" <jgg@...pe.ca>,
	"jhubbard@...dia.com" <jhubbard@...dia.com>,
	"peterx@...hat.com" <peterx@...hat.com>,
	"jannh@...gle.com" <jannh@...gle.com>,
	"pfalcato@...e.de" <pfalcato@...e.de>,
	"shuah@...nel.org" <shuah@...nel.org>,
	"seanjc@...gle.com" <seanjc@...gle.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>,
	"kvmarm@...ts.linux.dev" <kvmarm@...ts.linux.dev>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"bpf@...r.kernel.org" <bpf@...r.kernel.org>,
	"linux-kselftest@...r.kernel.org" <linux-kselftest@...r.kernel.org>,
	"Cali, Marco" <xmarcalx@...zon.co.uk>, "Kalyazin,
	Nikita" <kalyazin@...zon.co.uk>, "Thomson,
	Jack" <jackabt@...zon.co.uk>,
	"derekmn@...zon.co.uk" <derekmn@...zon.co.uk>,
	"tabba@...gle.com" <tabba@...gle.com>,
	"ackerleytng@...gle.com" <ackerleytng@...gle.com>
Subject: Re: [PATCH v7 05/12] KVM: guest_memfd: Add flag to remove from
 direct map

"Roy, Patrick" <roypat@...zon.co.uk> writes:

....

> +static int kvm_gmem_folio_zap_direct_map(struct folio *folio)
> +{
> +	if (kvm_gmem_folio_no_direct_map(folio))
> +		return 0;
> +
> +	int r = set_direct_map_valid_noflush(folio_page(folio, 0), folio_nr_pages(folio),
> +					 false);
> +
> +	if (!r) {
> +		unsigned long addr = (unsigned long) folio_address(folio);
> +		folio->private = (void *) ((u64) folio->private & KVM_GMEM_FOLIO_NO_DIRECT_MAP);
> +		flush_tlb_kernel_range(addr, addr + folio_size(folio));
> +	}
> +
> +	return r;
> +}

These 'noflush' functions are actually doing flush_tlb_kernel

[-]  ∘ flush_tlb_kernel_range
 |-[-]  ← __change_memory_common
 |  `-[-]  ← set_memory_valid
 |     `-   ← set_direct_map_valid_noflush

-aneesh