> -----Original Message----- > From: Andy Shevchenko [mailto:andy.shevchenko@xxxxxxxxx] > Sent: Tuesday, September 26, 2017 3:06 PM > To: Limonciello, Mario <Mario_Limonciello@xxxxxxxx> > Cc: dvhart@xxxxxxxxxxxxx; LKML <linux-kernel@xxxxxxxxxxxxxxx>; Platform Driver > <platform-driver-x86@xxxxxxxxxxxxxxx>; quasisec@xxxxxxxxxx; Pali Rohár > <pali.rohar@xxxxxxxxx> > Subject: Re: [PATCH v2 00/14] Introduce support for Dell SMBIOS over WMI > > On Tue, Sep 26, 2017 at 9:49 PM, Mario Limonciello > <mario.limonciello@xxxxxxxx> wrote: > > The existing way that the dell-smbios helper module and associated > > other drivers (dell-laptop, dell-wmi) communicate with the platform > > really isn't secure. It requires creating a buffer in physical > > DMA32 memory space and passing that to the platform via SMM. > > > > Since the platform got a physical memory pointer, you've just got > > to trust that the platform has only modified (and accessed) memory > > within that buffer. > > > > Dell Platform designers recognize this security risk and offer a > > safer way to communicate with the platform over ACPI. This is > > in turn exposed via a WMI interface to the OS. > > > > When communicating over WMI-ACPI the communication doesn't occur > > with physical memory pointers. When the ASL is invoked, the fixed > > length ACPI buffer is copied to a small operating region. The ASL > > will invoke the SMI, and SMM will only have access to this operating > > region. When the ASL returns the buffer is copied back for the OS > > to process. > > > > This method of communication should also deprecate the usage of the > > dcdbas kernel module and software dependent upon it's interface. > > Instead offer a character device interface for communicating with this > > ASL method to allow userspace to use instead. > > > > To faciliate that this patch series introduces a generic way for WMI > > drivers to be able to create discoverable character devices through > > the WMI bus when desired. > > Requiring WMI drivers to explicitly ask for this functionality will > > act as an effective vendor whitelist to character device creation. > > > > Thanks for an update, looks better now. > I'm in the middle of going through it and noticed that patches 6 and 7 > sound like a fix to me. > Perhaps better to move it to be first part of the series. In v2 I'd say that all of 1 through 7 are fixes that even if the rest of the series doesn't get pulled in immediately should land sooner. I'll reorder 6 and 7 for the beginning though for v3 if v3 is necessary. 8 through 13 are the real "meat", and 14 is a fixup. > > Please, include Andy Lutomirski to Cc list, I'm pretty sure he is > interested in changes like these to WMI. Added. Andy you weren't CC'ed on the original or v2 submission, but if this requires a v3 I'll include you. > > > changes between v1 and v2: > > * Introduce another patch to sort the includes in wmi.c > > * Introduce another patch to cleanup dell_wmi_check_descriptor_buffer > > checks. > > * Add a commit message to the pr_fmt commit > > * Introduce includes to wmi.c in proper location > > * Add Reviewed-by to relevant patches from Pali > > * Make the WMI introduction patch fallback to legacy SMI > > if compiled with CONFIG_DCDBAS > > * Separate format of WMI and SMI buffers. WMI buffer supports more > > arguments and data. > > * Adjust the rename patch for changes to fallback > > * Drop sysfs token creation patch > > * Adjust WMI descriptor check patch for changes to fallback > > * introduce another patch to remove needless includes in dell-smbios.c > > * Add token ioctl interface to character device. > > - Can query number of tokens > > - Can query values in all tokens > > * Expose format of all buffers and IOCTL commands to uapi header > > * Drop the read interface from character device. It doesn't make > > sense with multiple different ioctl methods. > > * Default WMI interface to 32k (This would normally be queried via > > MOF, but that's not possible yet) > > * Create separate buffers for WMI and SMI. If WMI is available, > > free the SMI buffer. > > * Reorder patches so all fixups come first in the series. > > > > Mario Limonciello (14): > > platform/x86: dell-wmi: label driver as handling notifications > > platform/x86: dell-smbios: drop needless includes > > platform/x86: dell-wmi: Don't match on descriptor GUID modalias > > platform/x86: dell-smbios: Add pr_fmt definition to driver > > platform/x86: wmi: sort include list > > platform/x86: wmi: Cleanup exit routine in reverse order of init > > platform/x86: wmi: destroy on cleanup rather than unregister > > platform/x86: dell-smbios: Introduce a WMI-ACPI interface > > platform/x86: dell-smbios: rename to dell-wmi-smbios > > platform/x86: dell-wmi-smbios: Use Dell WMI descriptor check > > platform/x86: wmi: create character devices when requested by drivers > > platform/x86: dell-wmi-smbios: introduce character device for > > userspace > > platform/x86: Kconfig: Change the default settings for dell-wmi-smbios > > platform/x86: dell-wmi-smbios: clean up wmi descriptor check > > > > Documentation/ABI/testing/dell-wmi-smbios | 10 + > > MAINTAINERS | 8 +- > > drivers/platform/x86/Kconfig | 13 +- > > drivers/platform/x86/Makefile | 2 +- > > drivers/platform/x86/dell-laptop.c | 2 +- > > drivers/platform/x86/dell-smbios.c | 213 --------- > > drivers/platform/x86/dell-wmi-smbios.c | 481 +++++++++++++++++++++ > > .../x86/{dell-smbios.h => dell-wmi-smbios.h} | 28 +- > > drivers/platform/x86/dell-wmi.c | 78 +--- > > drivers/platform/x86/wmi.c | 116 ++++- > > include/linux/wmi.h | 1 + > > include/uapi/linux/dell-wmi-smbios.h | 55 +++ > > 12 files changed, 674 insertions(+), 333 deletions(-) > > create mode 100644 Documentation/ABI/testing/dell-wmi-smbios > > delete mode 100644 drivers/platform/x86/dell-smbios.c > > create mode 100644 drivers/platform/x86/dell-wmi-smbios.c > > rename drivers/platform/x86/{dell-smbios.h => dell-wmi-smbios.h} (74%) > > create mode 100644 include/uapi/linux/dell-wmi-smbios.h > > > > -- > > 2.14.1 > > > > > > -- > With Best Regards, > Andy Shevchenko
