From: <dan.j.williams@intel.com>
To: Alexey Kardashevskiy <aik@amd.com>, <x86@kernel.org>
Cc: <linux-kernel@vger.kernel.org>, <kvm@vger.kernel.org>,
<linux-pci@vger.kernel.org>, Thomas Gleixner <tglx@linutronix.de>,
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Kuppuswamy Sathyanarayanan
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Geliang Tang <geliang@kernel.org>,
Piotr Gregor <piotrgregor@rsyncme.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
"Alex Williamson" <alex@shazbot.org>,
Arnd Bergmann <arnd@arndb.de>,
Jesse Barnes <jbarnes@virtuousgeek.org>,
Jacob Pan <jacob.jun.pan@linux.intel.com>,
Yinghai Lu <yinghai@kernel.org>,
Kevin Brodsky <kevin.brodsky@arm.com>,
Jonathan Cameron <jonathan.cameron@huawei.com>,
"Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>,
Xu Yilun <yilun.xu@linux.intel.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
Kim Phillips <kim.phillips@amd.com>,
"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
Stefano Stabellini <sstabellini@kernel.org>,
Claire Chang <tientzu@chromium.org>, <linux-coco@lists.linux.dev>,
<iommu@lists.linux.dev>, Alexey Kardashevskiy <aik@amd.com>
Subject: Re: [PATCH kernel 8/9] RFC: PCI: Avoid needless touching of Command register
Date: Wed, 25 Feb 2026 16:34:10 -0800 [thread overview]
Message-ID: <699f9502bd87b_1cc51001@dwillia2-mobl4.notmuch> (raw)
In-Reply-To: <20260225053806.3311234-9-aik@amd.com>
Alexey Kardashevskiy wrote:
> Once locked, a TDI's MSE and BME are not allowed to be cleared.
>
> Skip INTx test as TEE-capable PCI functions are most likely IOV VFs
> anyway and those do not support INTx at all.
>
> Add a quirk preventing the probing code from disabling MSE when
> updating 64bit BAR (which cannot be done atomically).
>
> Note that normally this happens too early and likely not really
> needed for the device attestation happening long after PCI probing.
>
> Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
> ---
>
> This is also handled in QEMU - it will block clearing BME and MSE
> (normally happening on modprobe/rmmod) as long as the TDI is
> CONFIG_LOCKED or RUN.
>
> This only patch is not enough but reduces the number of unwanted
> writes to MSE/BME.
>
> Also, SRIOV cannot have INTx so pci_intx_mask_broken() could skip
> VFs too, should it?
Locked command register management is handled by QEMU. This patch needs
quite a bit more explanation about what use case it is trying to solve.
next prev parent reply other threads:[~2026-02-26 0:34 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-25 5:37 [PATCH kernel 0/9] PCI/TSM: coco/sev-guest: Implement SEV-TIO PCIe TDISP (phase2) Alexey Kardashevskiy
2026-02-25 5:37 ` [PATCH kernel 1/9] pci/tsm: Add TDISP report blob and helpers to parse it Alexey Kardashevskiy
2026-02-25 6:16 ` dan.j.williams
2026-02-25 10:10 ` Arnd Bergmann
2026-02-26 0:09 ` Alexey Kardashevskiy
2026-02-26 2:34 ` dan.j.williams
2026-02-26 3:49 ` Alexey Kardashevskiy
2026-02-26 21:08 ` dan.j.williams
2026-02-25 5:37 ` [PATCH kernel 2/9] pci/tsm: Add tsm_tdi_status Alexey Kardashevskiy
2026-02-25 6:33 ` dan.j.williams
2026-02-25 23:42 ` Alexey Kardashevskiy
2026-03-02 6:58 ` Aneesh Kumar K.V
2026-02-25 5:37 ` [PATCH kernel 3/9] coco/sev-guest: Allow multiple source files in the driver Alexey Kardashevskiy
2026-02-25 5:37 ` [PATCH kernel 4/9] dma/swiotlb: Stop forcing SWIOTLB for TDISP devices Alexey Kardashevskiy
2026-02-25 16:30 ` dan.j.williams
2026-02-25 18:00 ` Robin Murphy
2026-02-25 20:57 ` dan.j.williams
2026-02-28 0:28 ` Jason Gunthorpe
2026-03-02 23:53 ` dan.j.williams
2026-03-03 0:19 ` Jason Gunthorpe
2026-03-03 0:29 ` dan.j.williams
2026-03-03 12:43 ` Jason Gunthorpe
2026-03-04 6:45 ` Alexey Kardashevskiy
2026-03-04 12:43 ` Jason Gunthorpe
2026-03-25 10:42 ` Alexey Kardashevskiy
2026-04-03 12:40 ` Alexey Kardashevskiy
2026-04-15 6:32 ` Alexey Kardashevskiy
2026-04-20 23:50 ` Jason Gunthorpe
2026-04-30 3:25 ` Alexey Kardashevskiy
2026-02-25 16:48 ` Robin Murphy
2026-02-26 0:09 ` Alexey Kardashevskiy
2026-03-02 7:54 ` Aneesh Kumar K.V
2026-02-25 5:37 ` [PATCH kernel 5/9] x86/mm: Stop forcing decrypted page state " Alexey Kardashevskiy
2026-02-25 16:51 ` dan.j.williams
2026-02-25 5:37 ` [PATCH kernel 6/9] x86/dma-direct: Stop changing encrypted " Alexey Kardashevskiy
2026-02-25 17:08 ` Robin Murphy
2026-02-25 21:35 ` dan.j.williams
2026-02-26 6:22 ` Alexey Kardashevskiy
2026-02-28 0:06 ` Jason Gunthorpe
2026-03-02 0:01 ` Alexey Kardashevskiy
2026-03-02 0:35 ` Jason Gunthorpe
2026-03-02 5:26 ` Alexey Kardashevskiy
2026-03-02 13:35 ` Jason Gunthorpe
2026-03-03 8:19 ` Alexey Kardashevskiy
2026-03-03 12:15 ` Jason Gunthorpe
2026-02-25 5:37 ` [PATCH kernel 7/9] coco/sev-guest: Implement the guest support for SEV TIO (phase2) Alexey Kardashevskiy
2026-02-25 6:00 ` Borislav Petkov
2026-02-26 3:39 ` Alexey Kardashevskiy
2026-02-26 19:52 ` Borislav Petkov
2026-02-25 5:37 ` [PATCH kernel 8/9] RFC: PCI: Avoid needless touching of Command register Alexey Kardashevskiy
2026-02-26 0:24 ` Bjorn Helgaas
2026-02-26 5:58 ` Alexey Kardashevskiy
2026-02-26 0:34 ` dan.j.williams [this message]
2026-02-25 5:37 ` [PATCH kernel 9/9] pci: Allow encrypted MMIO mapping via sysfs Alexey Kardashevskiy
2026-03-02 8:20 ` Aneesh Kumar K.V
2026-03-02 8:59 ` Alexey Kardashevskiy
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