From: Bjorn Helgaas <helgaas@kernel.org>
To: "Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>
Cc: "Bjorn Helgaas" <bhelgaas@google.com>,
"Jürgen Groß" <jgross@suse.com>,
"Roger Pau Monné" <roger.pau@citrix.com>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
xen-devel <xen-devel@lists.xenproject.org>,
linux-kernel@vger.kernel.org, regressions@lists.linux.dev,
"Felix Fietkau" <nbd@nbd.name>,
"Lorenzo Bianconi" <lorenzo@kernel.org>,
"Ryder Lee" <ryder.lee@mediatek.com>,
linux-pci@vger.kernel.org, "Jan Beulich" <jbeulich@suse.com>
Subject: Re: Config space access to Mediatek MT7922 doesn't work after device reset in Xen PV dom0 (regression, Linux 6.12)
Date: Wed, 29 Jan 2025 07:32:52 -0600 [thread overview]
Message-ID: <20250129133252.GA451735@bhelgaas> (raw)
In-Reply-To: <Z5mk0K5xltK6iZXN@mail-itl>
On Wed, Jan 29, 2025 at 04:47:28AM +0100, Marek Marczykowski-Górecki wrote:
> On Tue, Jan 28, 2025 at 09:40:18PM -0600, Bjorn Helgaas wrote:
> > I guess the code at [2] is running in user mode and uses Linux
> > syscalls for config access? Is it straceable?
>
> Nope, it's running as the hypervisor and mediates Linux's access to the
> hardware. In fact, Linux PV kernel (which dom0 is by default under Xen)
> is running in ring 3...
>
> But I can add some more logging there.
So I guess the hypervisor performs the config access on behalf of the
Linux PV kernel? Obviously Linux thinks CRS/RRS SV is enabled, but I
suppose all the lspci output is similarly based on whatever the
hypervisor does, so how do we know the actual hardware config?
> > > [2] https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/arch/x86/pv/emul-priv-op.c;h=70150c27227661baa253af8693ff00f2ab640a98;hb=HEAD#l295
next prev parent reply other threads:[~2025-01-29 13:32 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-01-17 12:05 Marek Marczykowski-Górecki
2025-01-29 1:15 ` Bjorn Helgaas
2025-01-29 2:10 ` Marek Marczykowski-Górecki
2025-01-29 3:03 ` Bjorn Helgaas
2025-01-29 3:22 ` Marek Marczykowski-Górecki
2025-01-29 3:40 ` Bjorn Helgaas
2025-01-29 3:47 ` Marek Marczykowski-Górecki
2025-01-29 13:32 ` Bjorn Helgaas [this message]
2025-01-29 13:52 ` Jan Beulich
2025-01-29 14:50 ` Bjorn Helgaas
2025-01-29 9:17 ` Jan Beulich
2025-01-29 11:53 ` Marek Marczykowski-Górecki
2025-01-29 12:49 ` Jan Beulich
2025-01-29 13:28 ` Bjorn Helgaas
2025-01-29 13:54 ` Jan Beulich
2025-01-29 18:48 ` Bjorn Helgaas
2025-01-30 4:55 ` Marek Marczykowski-Górecki
2025-01-30 9:30 ` Jan Beulich
2025-01-30 21:31 ` Bjorn Helgaas
2025-01-31 7:13 ` Jan Beulich
2025-01-31 8:36 ` Marek Marczykowski-Górecki
2025-02-05 22:14 ` Marek Marczykowski-Górecki
2025-02-07 22:00 ` Bjorn Helgaas
2025-02-07 22:10 ` Marek Marczykowski-Górecki
2025-02-07 22:23 ` Bjorn Helgaas
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