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From: Christoph Hellwig <hch@infradead.org>
To: "Kuppuswamy,
	Sathyanarayanan"  <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: "Michael S. Tsirkin" <mst@redhat.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>,
	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>,
	Andi Kleen <ak@linux.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 v4 11/15] pci: Add pci_iomap_shared{,_range}
Date: Tue, 24 Aug 2021 08:07:55 +0100	[thread overview]
Message-ID: <YSSay4zGjLaNMOh1@infradead.org> (raw)
In-Reply-To: <26a3cce5-ddf7-cbe6-a41e-58a2aea48f78@linux.intel.com>

On Mon, Aug 23, 2021 at 05:30:54PM -0700, Kuppuswamy, Sathyanarayanan wrote:
> 
> 
> On 8/23/21 4:56 PM, Michael S. Tsirkin wrote:
> > > Add a new variant of pci_iomap for mapping all PCI resources
> > > of a devices as shared memory with a hypervisor in a confidential
> > > guest.
> > > 
> > > Signed-off-by: Andi Kleen<ak@linux.intel.com>
> > > Signed-off-by: Kuppuswamy Sathyanarayanan<sathyanarayanan.kuppuswamy@linux.intel.com>
> > I'm a bit puzzled by this part. So why should the guest*not*  map
> > pci memory as shared? And if the answer is never (as it seems to be)
> > then why not just make regular pci_iomap DTRT?
> 
> It is in the context of confidential guest (where VMM is un-trusted). So
> we don't want to make all PCI resource as shared. It should be allowed
> only for hardened drivers/devices.

Well, assuming the host can do any damage when mapped shared that also
means not mapping it shared will completely break the drivers.

  parent reply	other threads:[~2021-08-24  7:11 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-05  0:52 [PATCH v4 00/15] Add TDX Guest Support (shared-mm support) Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 01/15] x86/mm: Move force_dma_unencrypted() to common code Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 02/15] x86/tdx: Exclude Shared bit from physical_mask Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 03/15] x86/tdx: Make pages shared in ioremap() Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 04/15] x86/tdx: Add helper to do MapGPA hypercall Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 05/15] x86/tdx: Make DMA pages shared Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 06/15] x86/kvm: Use bounce buffers for TD guest Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 07/15] x86/tdx: ioapic: Add shared bit for IOAPIC base address Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 08/15] x86/tdx: Enable shared memory protected guest flags for TDX guest Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 09/15] pci: Consolidate pci_iomap* and pci_iomap*wc Kuppuswamy Sathyanarayanan
2021-08-12 19:43   ` Bjorn Helgaas
2021-08-12 22:11     ` Andi Kleen
2021-08-12 22:29     ` Kuppuswamy, Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 10/15] asm/io.h: Add ioremap_shared fallback Kuppuswamy Sathyanarayanan
2021-08-12 19:46   ` Bjorn Helgaas
2021-08-13  7:58   ` Christoph Hellwig
2021-08-05  0:52 ` [PATCH v4 11/15] pci: Add pci_iomap_shared{,_range} Kuppuswamy Sathyanarayanan
2021-08-13  8:02   ` Christoph Hellwig
2021-08-23 23:56   ` Michael S. Tsirkin
2021-08-24  0:30     ` Kuppuswamy, Sathyanarayanan
2021-08-24  1:04       ` Dan Williams
2021-08-24  2:14         ` Andi Kleen
2021-08-24  9:47           ` Michael S. Tsirkin
2021-08-24 17:20             ` Andi Kleen
2021-08-24 18:55               ` Bjorn Helgaas
2021-08-24 20:14                 ` Andi Kleen
2021-08-24 20:31                   ` Bjorn Helgaas
2021-08-24 20:50                     ` Andi Kleen
2021-08-24 21:05                       ` Dan Williams
2021-08-25 14:52                       ` Bjorn Helgaas
2021-08-24 21:55                 ` Rajat Jain
2021-08-29 15:27               ` Michael S. Tsirkin
2021-08-29 16:17                 ` Andi Kleen
2021-08-29 22:26                   ` Michael S. Tsirkin
2021-08-30  5:11                     ` Andi Kleen
2021-08-30 20:59                       ` Michael S. Tsirkin
2021-08-31  0:23                         ` Andi Kleen
2021-09-10  9:54                           ` Michael S. Tsirkin
2021-09-10 16:34                             ` Andi Kleen
2021-09-11 23:54                               ` Michael S. Tsirkin
2021-09-13  5:53                                 ` Michael S. Tsirkin
2021-09-24 22:43                                 ` Andi Kleen
2021-09-27  9:07                                   ` Michael S. Tsirkin
2021-08-24 21:56         ` Rajat Jain
2021-08-24 21:59           ` Dan Williams
2021-08-24  7:07       ` Christoph Hellwig [this message]
2021-08-24 17:04         ` Andi Kleen
2021-08-29 15:34           ` Michael S. Tsirkin
2021-08-29 16:43             ` Andi Kleen
2021-08-24  9:12       ` Michael S. Tsirkin
2021-08-05  0:52 ` [PATCH v4 12/15] pci: Mark MSI data shared Kuppuswamy Sathyanarayanan
2021-08-13  8:07   ` Christoph Hellwig
2021-08-05  0:52 ` [PATCH v4 13/15] virtio: Use shared mappings for virtio PCI devices Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 14/15] x86/tdx: Implement ioremap_shared for x86 Kuppuswamy Sathyanarayanan
2021-08-05  0:52 ` [PATCH v4 15/15] x86/tdx: Add cmdline option to force use of ioremap_shared Kuppuswamy Sathyanarayanan

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