linux-kernel - RE: [PATCH 1/4] PCI: hv: Do not do vmbus initialization on baremetal

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID:
 <SN6PR02MB41574163515870DB8E430C56D475A@SN6PR02MB4157.namprd02.prod.outlook.com>
Date: Wed, 11 Jun 2025 23:06:23 +0000
From: Michael Kelley <mhklinux@...look.com>
To: Nuno Das Neves <nunodasneves@...ux.microsoft.com>,
	"linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-pci@...r.kernel.org"
	<linux-pci@...r.kernel.org>
CC: "kys@...rosoft.com" <kys@...rosoft.com>, "haiyangz@...rosoft.com"
	<haiyangz@...rosoft.com>, "wei.liu@...nel.org" <wei.liu@...nel.org>,
	"decui@...rosoft.com" <decui@...rosoft.com>, "catalin.marinas@....com"
	<catalin.marinas@....com>, "will@...nel.org" <will@...nel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>, "mingo@...hat.com"
	<mingo@...hat.com>, "bp@...en8.de" <bp@...en8.de>,
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>, "hpa@...or.com"
	<hpa@...or.com>, "lpieralisi@...nel.org" <lpieralisi@...nel.org>,
	"kw@...ux.com" <kw@...ux.com>, "manivannan.sadhasivam@...aro.org"
	<manivannan.sadhasivam@...aro.org>, "robh@...nel.org" <robh@...nel.org>,
	"bhelgaas@...gle.com" <bhelgaas@...gle.com>, "jinankjain@...ux.microsoft.com"
	<jinankjain@...ux.microsoft.com>, "skinsburskii@...ux.microsoft.com"
	<skinsburskii@...ux.microsoft.com>, "mrathor@...ux.microsoft.com"
	<mrathor@...ux.microsoft.com>, "x86@...nel.org" <x86@...nel.org>
Subject: RE: [PATCH 1/4] PCI: hv: Do not do vmbus initialization on baremetal

From: Nuno Das Neves <nunodasneves@...ux.microsoft.com> Sent: Tuesday, June 10, 2025 4:52 PM
> 
> From: Mukesh Rathor <mrathor@...ux.microsoft.com>

The patch Subject line is confusing to me. Perhaps this better captures
the intent:

 "PCI: hv: Don't load the driver for the root partition on a bare-metal hypervisor"

> 
> init_hv_pci_drv() is not relevant for root partition on baremetal as there
> is no vmbus. On nested (with a Windows L1 root), vmbus is present.

This needs more precision. init_hv_pci_drv() isn't what is
"not relevant". It's the entire driver that doesn't need to be loaded
because the root partition on a bare-metal hypervisor doesn't use
VMBus. It's only when the root partition is running on a nested
hypervisor that it uses VMBus, and hence may need the Hyper-V
PCI driver to be loaded.

> 
> Signed-off-by: Mukesh Rathor <mrathor@...ux.microsoft.com>
> Signed-off-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
> ---
>  drivers/pci/controller/pci-hyperv.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index b4f29ee75848..4d25754dfe2f 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -4150,6 +4150,9 @@ static int __init init_hv_pci_drv(void)
>  	if (!hv_is_hyperv_initialized())
>  		return -ENODEV;
> 
> +	if (hv_root_partition() && !hv_nested)
> +		return -ENODEV;
> +
>  	ret = hv_pci_irqchip_init();
>  	if (ret)
>  		return ret;
> --
> 2.34.1