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Message-ID: <Y+5immKTXCsjSysx@zn.tnic> Date: Thu, 16 Feb 2023 18:06:34 +0100 From: Borislav Petkov <bp@...en8.de> To: "Michael Kelley (LINUX)" <mikelley@...rosoft.com> Cc: Sean Christopherson <seanjc@...gle.com>, 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@....de" <hch@....de>, "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>, "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>, "dan.j.williams@...el.com" <dan.j.williams@...el.com>, "jane.chu@...cle.com" <jane.chu@...cle.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 v5 06/14] x86/ioremap: Support hypervisor specified range to map as encrypted On Thu, Feb 16, 2023 at 04:16:16PM +0000, Michael Kelley (LINUX) wrote: > Historically, callbacks like Sean proposed default to NULL and do nothing > unless they are explicitly set. The Hyper-V vTOM code would set the callback. > Is that not sufficient? Or in the two places where the callback would > be made, do you want to bracket with a test for being in a Hyper-V vTOM > VM? If so, then we're back to needing something like CC_ATTR_PARAVISOR > on which to gate the callbacks. > > Or do you mean something else entirely? See the second part of my reply. This thing... > > because there's the next crapola with > > > > https://lore.kernel.org/all/20230209072220.6836-4-jgross@suse.com/ > > > > because apparently hyperv does PAT but disables MTRRs for such vTOM > > SEV-SNP guests and ... madness. > > > > But that's not the only example - Xen has been doing this thing too. > > > > And Jürgen has been trying to address this in a clean way but it is > > a pain. > > > > What I don't want to have is a gazillion ways to check what needs to > > happen for which guest type. Because people who change the kernel to run > > on baremetal, will break them. And I can't blame them. We try to support > > all kinds of guests in the x86 code but this support should be plain and > > simple. ... here. We need a single way to test for this guest type and stick with it. I'd like for all guest types we support to be queried in a plain and simple way. Not: * CC_ATTR_GUEST_MEM_ENCRYPT * x86_platform.hyper.is_private_mmio(addr) * CC_ATTR_PARAVISOR to mean three different aspects of SEV-SNP guests using vTOM on Hyper-V. This is going to be a major mess which we won't support. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
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