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From: "Michael S. Tsirkin" <mst@redhat.com>
To: Andi Kleen <ak@linux.intel.com>
Cc: Kuppuswamy Sathyanarayanan 
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@kernel.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Richard Henderson <rth@twiddle.net>,
	Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	James E J Bottomley <James.Bottomley@hansenpartnership.com>,
	Helge Deller <deller@gmx.de>,
	"David S . Miller" <davem@davemloft.net>,
	Arnd Bergmann <arnd@arndb.de>, Jonathan Corbet <corbet@lwn.net>,
	Paolo Bonzini <pbonzini@redhat.com>,
	David Hildenbrand <david@redhat.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Peter H Anvin <hpa@zytor.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Tony Luck <tony.luck@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Kirill Shutemov <kirill.shutemov@linux.intel.com>,
	Sean Christopherson <seanjc@google.com>,
	Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	linux-pci@vger.kernel.org, linux-alpha@vger.kernel.org,
	linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
	sparclinux@vger.kernel.org, linux-arch@vger.kernel.org,
	linux-doc@vger.kernel.org,
	virtualization@lists.linux-foundation.org
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


  reply	other threads:[~2021-10-15  6:57 UTC|newest]

Thread overview: 85+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-09  0:36 [PATCH v5 00/16] Add TDX Guest Support (shared-mm support) Kuppuswamy Sathyanarayanan
2021-10-09  0:36 ` [PATCH v5 01/16] x86/mm: Move force_dma_unencrypted() to common code Kuppuswamy Sathyanarayanan
2021-10-20 16:11   ` Tom Lendacky
2021-10-20 16:43     ` Sathyanarayanan Kuppuswamy
2021-10-09  0:36 ` [PATCH v5 02/16] x86/tdx: Get TD execution environment information via TDINFO Kuppuswamy Sathyanarayanan
2021-10-09  0:36 ` [PATCH v5 03/16] x86/tdx: Exclude Shared bit from physical_mask Kuppuswamy Sathyanarayanan
2021-11-05 22:11   ` Sean Christopherson
2021-11-08 14:45     ` Kirill A. Shutemov
2021-10-09  0:36 ` [PATCH v5 04/16] x86/tdx: Make pages shared in ioremap() Kuppuswamy Sathyanarayanan
2021-10-20 16:03   ` Tom Lendacky
2021-10-20 16:41     ` Sathyanarayanan Kuppuswamy
2021-10-09  0:37 ` [PATCH v5 05/16] x86/tdx: Add helper to do MapGPA hypercall Kuppuswamy Sathyanarayanan
2021-10-09  0:37 ` [PATCH v5 06/16] x86/tdx: Make DMA pages shared Kuppuswamy Sathyanarayanan
2021-10-20 16:33   ` Tom Lendacky
2021-10-20 16:45     ` Sathyanarayanan Kuppuswamy
2021-10-20 17:22       ` Tom Lendacky
2021-10-20 17:26         ` Sathyanarayanan Kuppuswamy
2021-10-09  0:37 ` [PATCH v5 07/16] x86/kvm: Use bounce buffers for TD guest Kuppuswamy Sathyanarayanan
2021-10-20 16:39   ` Tom Lendacky
2021-10-20 16:50     ` Sathyanarayanan Kuppuswamy
2021-10-20 17:26       ` Tom Lendacky
2021-10-09  0:37 ` [PATCH v5 08/16] x86/tdx: ioapic: Add shared bit for IOAPIC base address Kuppuswamy Sathyanarayanan
2021-10-09  0:37 ` [PATCH v5 09/16] x86/tdx: Enable shared memory confidential guest flags for TDX guest Kuppuswamy Sathyanarayanan
2021-10-09  0:37 ` [PATCH v5 10/16] PCI: Consolidate pci_iomap_range(), pci_iomap_wc_range() Kuppuswamy Sathyanarayanan
2021-10-09  0:37 ` [PATCH v5 11/16] asm/io.h: Add ioremap_host_shared fallback Kuppuswamy Sathyanarayanan
2021-10-09  0:37 ` [PATCH v5 12/16] PCI: Add pci_iomap_host_shared(), pci_iomap_host_shared_range() Kuppuswamy Sathyanarayanan
2021-10-09  9:53   ` 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
2021-10-12 18:36         ` Reshetova, Elena
2021-10-12 18:38           ` Andi Kleen
2021-10-12 18:57             ` Reshetova, Elena
2021-10-12 19:13               ` Dan Williams
2021-10-12 19:49                 ` Andi Kleen
2021-10-12 21:11           ` Michael S. Tsirkin
2021-10-14  6:32             ` Reshetova, Elena
2021-10-14  6:57               ` Michael S. Tsirkin
2021-10-14  7:27                 ` Reshetova, Elena
2021-10-14  9:26                   ` Michael S. Tsirkin
2021-10-14 12:33                     ` Reshetova, Elena
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  7:03                 ` Reshetova, Elena
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
2021-10-09  0:37 ` [PATCH v5 13/16] PCI: Mark MSI data shared Kuppuswamy Sathyanarayanan
2021-10-09  0:37 ` [PATCH v5 14/16] virtio: Use shared mappings for virtio PCI devices Kuppuswamy Sathyanarayanan
2021-10-09  0:37 ` [PATCH v5 15/16] x86/tdx: Implement ioremap_host_shared for x86 Kuppuswamy Sathyanarayanan
2021-10-09  0:37 ` [PATCH v5 16/16] x86/tdx: Add cmdline option to force use of ioremap_host_shared Kuppuswamy Sathyanarayanan
2021-10-09  1:45   ` Randy Dunlap
2021-10-09  2:10     ` Kuppuswamy, Sathyanarayanan
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]
2021-10-15 13:34                         ` Andi Kleen
2021-10-17 22:34                           ` Michael S. Tsirkin

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