linux-kernel - RE: [PATCH] PCI/ACPI: Disable AER when

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 for Android: free password hash cracker in your pocket

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

Message-ID: <DM5PR12MB191612888094C4794951FAE4F8160@DM5PR12MB1916.namprd12.prod.outlook.com>
Date:   Thu, 11 Jan 2018 17:48:21 +0000
From:   "Ghannam, Yazen" <Yazen.Ghannam@....com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
CC:     ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        Linux PCI <linux-pci@...r.kernel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        "Bjorn Helgaas" <bhelgaas@...gle.com>, Borislav Petkov <bp@...e.de>
Subject: RE: [PATCH] PCI/ACPI: Disable AER when _OSC control bit is clear.

> -----Original Message-----
> From: rjwysocki@...il.com [mailto:rjwysocki@...il.com] On Behalf Of
> Rafael J. Wysocki
> Sent: Thursday, January 11, 2018 12:39 PM
> To: Ghannam, Yazen <Yazen.Ghannam@....com>
> Cc: ACPI Devel Maling List <linux-acpi@...r.kernel.org>; Linux Kernel Mailing
> List <linux-kernel@...r.kernel.org>; Linux PCI <linux-pci@...r.kernel.org>;
> Rafael J. Wysocki <rjw@...ysocki.net>; Len Brown <lenb@...nel.org>; Bjorn
> Helgaas <bhelgaas@...gle.com>; Borislav Petkov <bp@...e.de>
> Subject: Re: [PATCH] PCI/ACPI: Disable AER when _OSC control bit is clear.
> 
> On Thu, Jan 11, 2018 at 4:03 PM, Yazen Ghannam
> <Yazen.Ghannam@....com> wrote:
> > From: Yazen Ghannam <yazen.ghannam@....com>
> >
> > Currently, aer_service_init() checks if AER is available and that
> > Firmware First handling is not enabled. The _OSC request for AER is
> > not taken into account when deciding to enable AER in Linux.
> >
> > We should check that the _OSC control for AER is set. If it's not
> > then AER should be disabled.
> >
> > The _OSC control for AER is not requested when APEI Firmware First is
> > used, so the same condition applies.
> >
> > Mark AER as disabled if the _OSC request was not made or accepted.
> >
> > Remove redunant check for aer_acpi_firmware_first() when calling
> > aer_service_init(), since this is check is already included when
> > checking the _OSC control.
> >
> > Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
> > ---
> >  drivers/acpi/pci_root.c       | 3 +++
> >  drivers/pci/pcie/aer/aerdrv.c | 2 +-
> >  2 files changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
> > index 6fc204a52493..19a625ed8de9 100644
> > --- a/drivers/acpi/pci_root.c
> > +++ b/drivers/acpi/pci_root.c
> > @@ -512,6 +512,9 @@ static void negotiate_os_control(struct
> acpi_pci_root *root, int *no_aspm)
> >                  */
> >                 *no_aspm = 1;
> >         }
> > +
> > +       if (!(requested & control & OSC_PCI_EXPRESS_AER_CONTROL))
> 
> One of the operators above needs to be a && I suppose?
> 

It's a 3-way bitwise AND to check that OSC_PCI_EXPRESS_AER_CONTROL is
set in both "requested" and "control".

IOW, we check if AER was requested by the OS and that the platform
granted the request.

Thanks,
Yazen