On Wed, Jan 29, 2020 at 08:20:34PM +0000, Wei Liu wrote:
> VP assist page is rather important as we need to toggle some bits in it
> for efficient nested virtualisation.
>
> Signed-off-by: Wei Liu <li...@microsoft.com>
> ---
> v5:
> 1. Deal with error properly instead of always panicking
> 2. Swap percpu variables declarations' location
>
> v4:
> 1. Use private.h
> 2. Prevent leak
>
> v3:
> 1. Use xenheap page
> 2. Drop set_vp_assist
>
> v2:
> 1. Use HV_HYP_PAGE_SHIFT instead
> ---
> xen/arch/x86/guest/hyperv/hyperv.c | 44 ++++++++++++++++++++++++++++-
> xen/arch/x86/guest/hyperv/private.h | 1 +
> 2 files changed, 44 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/x86/guest/hyperv/hyperv.c
> b/xen/arch/x86/guest/hyperv/hyperv.c
> index af0d6ed692..bc40a3d338 100644
> --- a/xen/arch/x86/guest/hyperv/hyperv.c
> +++ b/xen/arch/x86/guest/hyperv/hyperv.c
> @@ -31,6 +31,7 @@
>
> struct ms_hyperv_info __read_mostly ms_hyperv;
> DEFINE_PER_CPU_READ_MOSTLY(void *, hv_pcpu_input_page);
> +DEFINE_PER_CPU_READ_MOSTLY(void *, hv_vp_assist);
> DEFINE_PER_CPU_READ_MOSTLY(unsigned int, hv_vp_index);
>
> static uint64_t generate_guest_id(void)
> @@ -155,16 +156,57 @@ static int setup_hypercall_pcpu_arg(void)
> return 0;
> }
>
> +static int setup_vp_assist(void)
> +{
> + void *mapping;
> + uint64_t val;
> +
> + mapping = this_cpu(hv_vp_assist);
You could also avoid the usage of the local mapping variable here.
> +
> + if ( !mapping )
> + {
> + mapping = alloc_xenheap_page();
> + if ( !mapping )
> + {
> + printk("Failed to allocate vp_assist page for CPU%u\n",
> + smp_processor_id());
> + return -ENOMEM;
> + }
> +
> + clear_page(mapping);
> + this_cpu(hv_vp_assist) = mapping;
> + }
> +
> + val = (virt_to_mfn(mapping) << HV_HYP_PAGE_SHIFT)
There's virt_to_maddr which would avoid the shift.
> + | HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
> + wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
> +
> + return 0;
> +}
> +
> static void __init setup(void)
> {
> setup_hypercall_page();
> +
> if ( setup_hypercall_pcpu_arg() )
> panic("Hypercall percpu arg setup failed\n");
> +
> + if ( setup_vp_assist() )
> + panic("VP assist page setup failed\n");
> }
>
> static int ap_setup(void)
> {
> - return setup_hypercall_pcpu_arg();
> + int rc;
> +
> + rc = setup_hypercall_pcpu_arg();
> + if ( rc )
> + goto out;
No need for a label, as just returning here would make the function
shorter:
rc = setup_hypercall_pcpu_arg();
if ( rc )
return rc;
return setup_vp_assist();
Thanks, Roger.
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