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From: Leon Romanovsky <leon@kernel.org>
To: "Popov, Pavel E" <pavel.e.popov@intel.com>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
	Jim Chow <jim.chow@broadcom.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	Radu Rugina <radu.rugina@broadcom.com>,
	Alexey Makhalov <alexey.makhalov@broadcom.com>,
	Wei Liu <wei.liu@kernel.org>,
	Michael Kelley <mhklinux@outlook.com>,
	Lukas Wunner <lukas@wunner.de>,
	Nathan Ciobanu <nathan.d.ciobanu@linux.intel.com>,
	"bcm-kernel-feedback-list@broadcom.com"
	<bcm-kernel-feedback-list@broadcom.com>,
	"virtualization@lists.linux.dev" <virtualization@lists.linux.dev>,
	"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
	"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/2] PCI/P2PDMA: Allow P2PDMA in VMware and Hyper-V guests on Intel hosts
Date: Sun, 11 Oct 2026 08:47:00 +0300	[thread overview]
Message-ID: <20261011054700.GF11438@unreal> (raw)
In-Reply-To: <LV2PR11MB60707DAD12BFBEAB681463B7B2922@LV2PR11MB6070.namprd11.prod.outlook.com>

On Fri, Oct 09, 2026 at 07:13:31PM +0000, Popov, Pavel E wrote:
> Leon,
> 
> Understood on all points, and I agree HMAT is the proper fix. We discussed
> it with Lukas Wunner as well. Exposing HMAT is on the hypervisor side; Jim
> Chow from VMware can speak to their plans. Even once HMAT lands in Linux,
> it only helps guests after the hypervisors add support for it.
> 
> The key point for us is that today there is no path at all for
> passthrough devices on VMware or Hyper-V, and that is what this patch
> addresses. We reviewed it with VMware and aligned on this approach for the
> guest in the meantime.

This does not change the fact that the patch causes unpredictable behavior for
P2P devices in the guest. Sometimes it works; other times, devices that
previously worked may be classified as P2P-capable and will stop.

> 
> Is there anything you would recommend to make the series acceptable as an
> interim?

Help Lukas and Mahesh succeed in their work.

Thanks

  reply	other threads:[~2026-10-11  5:47 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-09 15:40 Pavel Popov
2026-10-09 15:40 ` [PATCH 1/2] PCI/P2PDMA: Allow P2PDMA in VMware " Pavel Popov
2026-10-09 16:38   ` Logan Gunthorpe
2026-10-09 16:49     ` Popov, Pavel E
2026-10-09 15:40 ` [PATCH 2/2] PCI/P2PDMA: Allow P2PDMA in Hyper-V " Pavel Popov
2026-10-09 16:58 ` [PATCH 0/2] PCI/P2PDMA: Allow P2PDMA in VMware and " Bjorn Helgaas
2026-10-09 18:08   ` Leon Romanovsky
2026-10-09 18:21     ` Popov, Pavel E
2026-10-09 18:49       ` Leon Romanovsky
2026-10-09 19:13         ` Popov, Pavel E
2026-10-11  5:47           ` Leon Romanovsky [this message]
2026-10-09 19:12     ` Bjorn Helgaas

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