Re: [PATCH v2 1/2] PCI/P2PDMA: Allow P2PDMA in VMware guests on Intel hosts

[sashiko-bot@kernel.org]

> Peer-to-Peer DMA (P2PDMA) between two devices requires either a shared
> upstream bridge or a host bridge matching pci_p2pdma_whitelist[]. In
> VMware guests, passthrough devices appear directly on virtual root
> buses without host bridge devices. Consequently, P2PDMA checks
> evaluate endpoint Device IDs against the host bridge whitelist,
> causing P2PDMA requests to fail regardless of host support.
> 
> This affects discrete devices such as GPUs, NICs and NVMe drives.
> 
> The P2PDMA host bridge check does not work in a VMware guest. Bypass it
> for host CPUs whose host bridges are in pci_p2pdma_whitelist[] without
> restrictions. The list covers the Intel Xeon server generations from
> Skylake-SP to Diamond Rapids. AMD Zen and newer are already covered by
> cpu_supports_p2pdma(), so only Intel entries are needed.
> 
> Tested with the Intel Level Zero P2P benchmark (ze_peer) on Arc Pro B60
> cards in a Linux guest on VMware ESXi 9.0 (Emerald Rapids host).
> 
> Signed-off-by: Pavel Popov <pavel.e.popov@intel.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261016223402.19991-1-pavel.e.popov@intel.com?part=1