linux-kernel - RE: [PATCH v2 02/12] x86/ioapic: Gate decrypted mapping on cc_platform

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 for Android: free password hash cracker in your pocket

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

Date:   Mon, 14 Nov 2022 16:54:38 +0000
From:   "Michael Kelley (LINUX)" <mikelley@...rosoft.com>
To:     Dave Hansen <dave.hansen@...el.com>,
        "hpa@...or.com" <hpa@...or.com>, KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "wei.liu@...nel.org" <wei.liu@...nel.org>,
        Dexuan Cui <decui@...rosoft.com>,
        "luto@...nel.org" <luto@...nel.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "edumazet@...gle.com" <edumazet@...gle.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "pabeni@...hat.com" <pabeni@...hat.com>,
        "lpieralisi@...nel.org" <lpieralisi@...nel.org>,
        "robh@...nel.org" <robh@...nel.org>, "kw@...ux.com" <kw@...ux.com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "arnd@...db.de" <arnd@...db.de>,
        "hch@...radead.org" <hch@...radead.org>,
        "m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "thomas.lendacky@....com" <thomas.lendacky@....com>,
        "brijesh.singh@....com" <brijesh.singh@....com>,
        "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>,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        "sathyanarayanan.kuppuswamy@...ux.intel.com" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>,
        "isaku.yamahata@...el.com" <isaku.yamahata@...el.com>,
        "Williams, Dan J" <dan.j.williams@...el.com>,
        "jane.chu@...cle.com" <jane.chu@...cle.com>,
        "seanjc@...gle.com" <seanjc@...gle.com>,
        "tony.luck@...el.com" <tony.luck@...el.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>
Subject: RE: [PATCH v2 02/12] x86/ioapic: Gate decrypted mapping on
 cc_platform_has() attribute

From: Dave Hansen <dave.hansen@...el.com> Sent: Monday, November 14, 2022 8:23 AM
> 
> On 11/11/22 20:48, Michael Kelley (LINUX) wrote:
> > From: Dave Hansen <dave.hansen@...el.com> Sent: Friday, November 11, 2022 4:22
> PM
> >> On 11/10/22 22:21, Michael Kelley wrote:
> >>>  	 * Ensure fixmaps for IOAPIC MMIO respect memory encryption pgprot
> >>>  	 * bits, just like normal ioremap():
> >>>  	 */
> >>> -	flags = pgprot_decrypted(flags);
> >>> +	if (!cc_platform_has(CC_ATTR_HAS_PARAVISOR))
> >>> +		flags = pgprot_decrypted(flags);
> >> This begs the question whether *all* paravisors will want to avoid a
> >> decrypted ioapic mapping.  Is this _fundamental_ to paravisors, or it is
> >> an implementation detail of this _individual_ paravisor?
> > Hard to say.  The paravisor that Hyper-V provides for use with the vTOM
> > option in a SEV SNP VM is the only paravisor I've seen.  At least as defined
> > by Hyper-V and AMD SNP Virtual Machine Privilege Levels (VMPLs), the
> > paravisor resides within the VM trust boundary.  Anything that a paravisor
> > emulates would be in the "private" (i.e., encrypted) memory so it can be
> > accessed by both the guest OS and the paravisor.  But nothing fundamental
> > says that IOAPIC emulation *must* be done in the paravisor.
> 
> Please just make this check more specific.  Either make this a specific
> Hyper-V+SVM check, or rename it HAS_EMULATED_IOAPIC, like you were
> thinking.  If paravisors catch on and we end up with ten more of these
> things across five different paravisors and see a pattern, *then* a
> paravisor-specific one makes sense.

I'm good with that.  I'll use HAS_EMULATED_IOAPIC in v3.

Michael