From: Andi Kleen <ak@linux.intel.com>
To: Dan Williams <dan.j.williams@intel.com>,
"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>,
Kirill Shutemov <kirill.shutemov@linux.intel.com>,
Sean Christopherson <seanjc@google.com>,
Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
X86 ML <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux PCI <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 <linux-arch@vger.kernel.org>,
Linux Doc Mailing List <linux-doc@vger.kernel.org>,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v4 11/15] pci: Add pci_iomap_shared{,_range}
Date: Mon, 23 Aug 2021 19:14:18 -0700 [thread overview]
Message-ID: <d992b5af-8d57-6aa6-bd49-8e2b8d832b19@linux.intel.com> (raw)
In-Reply-To: <CAPcyv4iJVQKJ3bVwZhD08c8GNEP0jW2gx=H504NXcYK5o2t01A@mail.gmail.com>
On 8/23/2021 6:04 PM, Dan Williams wrote:
> On Mon, Aug 23, 2021 at 5:31 PM Kuppuswamy, Sathyanarayanan
> <sathyanarayanan.kuppuswamy@linux.intel.com> 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.
> That's confusing, isn't device authorization what keeps unaudited
> drivers from loading against untrusted devices? I'm feeling like
> Michael that this should be a detail that drivers need not care about
> explicitly, in which case it does not need to be exported because the
> detail can be buried in lower levels.
We originally made it default (similar to AMD), but it during code audit
we found a lot of drivers who do ioremap early outside the probe
function. Since it would be difficult to change them all we made it
opt-in, which ensures that only drivers that have been enabled can talk
with the host at all and can't be attacked. That made the problem of
hardening all these drivers a lot more practical.
Currently we only really need virtio and MSI-X shared, so for changing
two places in the tree you avoid a lot of headache elsewhere.
Note there is still a command line option to override if you want to
allow and load other drivers.
-Andi
next prev parent reply other threads:[~2021-08-24 2:14 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 [this message]
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
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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