>>> On 23.02.12 at 23:31, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> 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).
> 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?
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@xxxxxxxxxx>
> 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;
--
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