lkml.org 
[lkml]   [2012]   [Feb]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    SubjectRe: [PATCH] processor passthru - upload _Cx and _Pxx data to hypervisor (v5).
    On Fri, Feb 24, 2012 at 10:23:42AM +0000, Jan Beulich wrote:
    > >>> On 23.02.12 at 23:31, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote:
    > > This module (processor-passthru) collects the information that the cpufreq
    > > drivers and the ACPI processor code save in the 'struct acpi_processor' and
    > > then uploads it to the hypervisor.
    >
    > Thus looks conceptually wrong to me - there shouldn't be a need for a
    > CPUFreq driver to be loaded in Dom0 (or your module should masquerade
    > as the one and only suitable one).

    I piggyback on the generic cpufreq drivers to collect the information they
    have evaluated.

    I can make the driver a cpufreq one but there does not seem to be a way
    from the kernel to force a specific driver to say "use me". I could write
    it naturally, but not sure what the usage case is except for the driver
    I wrote. But perhaps there is also for the cpufreq powernow-k8 and acpi-processor
    so that they can function without the need for strict compile order
    (where powernow-k8 MUST be loaded before acpi-processor).

    >
    > > On the hypervisor side, it requires this patch on AMD:
    > > # HG changeset patch
    > > # Parent aea8cfac8cf1afe397f2e1d422a852008d8a83fe
    > > traps: AMD PM RDMSRs (MSR_K8_PSTATE_CTRL, etc)
    > >
    > > The restriction to read and write the AMD power management MSRs is gated if
    > > the
    > > domain 0 is the PM domain (so FREQCTL_dom0_kernel is set). But we can
    > > relax this restriction and allow the privileged domain to read the MSRs
    > > (but not write). This allows the priviliged domain to harvest the power
    > > management information (ACPI _PSS states) and send it to the hypervisor.
    >
    > Why would accessing these MSRs be necessary here, when it isn't
    > for non-pvops? Perhaps only because you want a CPUFreq driver
    > loaded?

    Correct. The powernow-k8
    >
    > Jan
    >
    > > This patch works fine with older classic dom0 (2.6.32) and with
    > > AMD K7 and K8 boxes.
    > >
    > > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    > > diff -r aea8cfac8cf1 xen/arch/x86/traps.c
    > > --- a/xen/arch/x86/traps.c Thu Feb 23 13:23:02 2012 -0500
    > > +++ b/xen/arch/x86/traps.c Thu Feb 23 13:29:00 2012 -0500
    > > @@ -2484,7 +2484,7 @@ static int emulate_privileged_op(struct
    > > case MSR_K8_PSTATE7:
    > > if ( boot_cpu_data.x86_vendor != X86_VENDOR_AMD )
    > > goto fail;
    > > - if ( !is_cpufreq_controller(v->domain) )
    > > + if ( !is_cpufreq_controller(v->domain) && !IS_PRIV(v->domain) )
    > > {
    > > regs->eax = regs->edx = 0;
    > > break;
    >
    >


    \
     
     \ /
      Last update: 2012-02-24 16:13    [W:4.114 / U:0.148 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site