From: "Michael S. Tsirkin" <mst@redhat.com>
To: Andi Kleen <ak@linux.intel.com>
Cc: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
linux-pci@vger.kernel.org, linux-mips@vger.kernel.org,
James E J Bottomley <James.Bottomley@hansenpartnership.com>,
Dave Hansen <dave.hansen@intel.com>,
Peter H Anvin <hpa@zytor.com>,
sparclinux@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Andrea Arcangeli <aarcange@redhat.com>,
Jonathan Corbet <corbet@lwn.net>, Helge Deller <deller@gmx.de>,
x86@kernel.org, Ingo Molnar <mingo@redhat.com>,
linux-arch@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
Tony Luck <tony.luck@intel.com>, Borislav Petkov <bp@alien8.de>,
Andy Lutomirski <luto@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Dan Williams <dan.j.williams@intel.com>,
virtualization@lists.linux-foundation.org,
Richard Henderson <rth@twiddle.net>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
linux-parisc@vger.kernel.org,
Sean Christopherson <seanjc@google.com>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-alpha@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
"David S . Miller" <davem@davemloft.net>,
Kirill Shutemov <kirill.shutemov@linux.intel.com>
Subject: Re: [PATCH v5 16/16] x86/tdx: Add cmdline option to force use of ioremap_host_shared
Date: Fri, 15 Oct 2021 02:57:16 -0400 [thread overview]
Message-ID: <20211015024923-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <c2ce5ad8-4df7-3a37-b235-8762a76b1fd3@linux.intel.com>
On Thu, Oct 14, 2021 at 10:50:59PM -0700, Andi Kleen wrote:
>
> > I thought you basically create an OperationRegion of SystemMemory type,
> > and off you go. Maybe the OSPM in Linux is clever and protects
> > some memory, I wouldn't know.
>
>
> I investigated this now, and it looks like acpi is using ioremap_cache(). We
> can hook into that and force non sharing. It's probably safe to assume that
> this is not used on real IO devices.
>
> I think there are still some other BIOS mappings that use just plain
> ioremap() though.
>
>
> -Andi
Hmm don't you mean the reverse? If you make ioremap shared then OS is
protected from malicious ACPI? If you don't make it shared then
malicious ACPI can poke at arbitrary OS memory. Looks like making
ioremap non shared by default is actually less safe than shared.
Interesting.
For BIOS I suspect there's no way around it, it needs to be
audited since it's executable.
--
MST
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next prev parent reply other threads:[~2021-10-15 6:57 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20211009003711.1390019-1-sathyanarayanan.kuppuswamy@linux.intel.com>
[not found] ` <20211009003711.1390019-17-sathyanarayanan.kuppuswamy@linux.intel.com>
2021-10-09 1:45 ` [PATCH v5 16/16] x86/tdx: Add cmdline option to force use of ioremap_host_shared Randy Dunlap
2021-10-09 11:04 ` Michael S. Tsirkin
2021-10-11 2:39 ` Andi Kleen
2021-10-11 12:04 ` Michael S. Tsirkin
2021-10-11 17:35 ` Andi Kleen
2021-10-11 18:28 ` Michael S. Tsirkin
2021-10-12 17:55 ` Andi Kleen
2021-10-12 20:59 ` Michael S. Tsirkin
2021-10-12 21:18 ` Andi Kleen
2021-10-12 21:30 ` Michael S. Tsirkin
2021-10-15 5:50 ` Andi Kleen
2021-10-15 6:57 ` Michael S. Tsirkin [this message]
[not found] ` <20211009003711.1390019-13-sathyanarayanan.kuppuswamy@linux.intel.com>
2021-10-09 9:53 ` [PATCH v5 12/16] PCI: Add pci_iomap_host_shared(), pci_iomap_host_shared_range() Michael S. Tsirkin
2021-10-09 20:39 ` Dan Williams
2021-10-10 22:11 ` Andi Kleen
2021-10-12 17:42 ` Dan Williams
2021-10-12 18:35 ` Andi Kleen
2021-10-12 21:14 ` Dan Williams
2021-10-12 21:18 ` Michael S. Tsirkin
2021-10-12 21:24 ` Andi Kleen
2021-10-12 21:28 ` Andi Kleen
2021-10-12 22:00 ` Dan Williams
2021-10-18 12:13 ` Greg KH
[not found] ` <DM8PR11MB57501C8F8F5C8B315726882EE7B69@DM8PR11MB5750.namprd11.prod.outlook.com>
2021-10-12 18:38 ` Andi Kleen
[not found] ` <DM8PR11MB57505C520763DF706309E177E7B69@DM8PR11MB5750.namprd11.prod.outlook.com>
2021-10-12 19:13 ` Dan Williams
2021-10-12 19:49 ` Andi Kleen
2021-10-12 21:11 ` Michael S. Tsirkin
[not found] ` <DM8PR11MB5750A40FAA6AFF6A29CF70DAE7B89@DM8PR11MB5750.namprd11.prod.outlook.com>
2021-10-14 6:57 ` Michael S. Tsirkin
[not found] ` <DM8PR11MB57500B2D821E8AAF93EB66CEE7B89@DM8PR11MB5750.namprd11.prod.outlook.com>
2021-10-14 9:26 ` Michael S. Tsirkin
[not found] ` <DM8PR11MB57505AAA1E1209F7FCA69C11E7B89@DM8PR11MB5750.namprd11.prod.outlook.com>
2021-10-17 22:17 ` Michael S. Tsirkin
2021-10-14 11:49 ` Michael S. Tsirkin
2021-10-17 21:52 ` Thomas Gleixner
2021-10-18 0:55 ` Thomas Gleixner
2021-10-18 1:10 ` Thomas Gleixner
2021-10-18 12:08 ` Greg KH
2021-10-10 22:22 ` Andi Kleen
2021-10-11 11:59 ` Michael S. Tsirkin
2021-10-11 17:32 ` Andi Kleen
2021-10-11 18:22 ` Michael S. Tsirkin
2021-10-18 12:15 ` Greg KH
2021-10-18 13:17 ` Michael S. Tsirkin
2021-10-11 7:58 ` Christoph Hellwig
2021-10-11 17:23 ` Andi Kleen
2021-10-11 19:09 ` Michael S. Tsirkin
2021-10-12 5:31 ` Christoph Hellwig
2021-10-12 18:37 ` Andi Kleen
[not found] ` <20211009003711.1390019-5-sathyanarayanan.kuppuswamy@linux.intel.com>
2021-10-20 16:03 ` [PATCH v5 04/16] x86/tdx: Make pages shared in ioremap() Tom Lendacky via Virtualization
[not found] ` <20211009003711.1390019-2-sathyanarayanan.kuppuswamy@linux.intel.com>
2021-10-20 16:11 ` [PATCH v5 01/16] x86/mm: Move force_dma_unencrypted() to common code Tom Lendacky via Virtualization
[not found] ` <20211009003711.1390019-7-sathyanarayanan.kuppuswamy@linux.intel.com>
2021-10-20 16:33 ` [PATCH v5 06/16] x86/tdx: Make DMA pages shared Tom Lendacky via Virtualization
[not found] ` <66acafb6-7659-7d76-0f52-d002cfae9cc8@linux.intel.com>
2021-10-20 17:22 ` Tom Lendacky via Virtualization
[not found] ` <20211009003711.1390019-8-sathyanarayanan.kuppuswamy@linux.intel.com>
2021-10-20 16:39 ` [PATCH v5 07/16] x86/kvm: Use bounce buffers for TD guest Tom Lendacky via Virtualization
[not found] ` <0a9c6485-74d8-e0fc-d261-097380272e07@linux.intel.com>
2021-10-20 17:26 ` Tom Lendacky via Virtualization
[not found] ` <20211009003711.1390019-4-sathyanarayanan.kuppuswamy@linux.intel.com>
[not found] ` <YYWsJFP31vpCAVFg@google.com>
2021-11-08 14:45 ` [PATCH v5 03/16] x86/tdx: Exclude Shared bit from physical_mask Kirill A. Shutemov
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