From: Wei Liu <wei.liu....@gmail.com> On Behalf Of Wei Liu Sent: Sunday,
December 29, 2019 10:34 AM
>
> VP assist page is rather important as we need to toggle some bits in
> that page such that L1 guest can make hypercalls directly to L0 Hyper-V.
>
> Preemptively split out set_vp_assist page which will be used in the resume
> path.
>
> Signed-off-by: Wei Liu <li...@microsoft.com>
> ---
> xen/arch/x86/guest/hyperv/hyperv.c | 35 ++++++++++++++++++++++++++++++
> xen/include/asm-x86/guest/hyperv.h | 1 +
> 2 files changed, 36 insertions(+)
>
> diff --git a/xen/arch/x86/guest/hyperv/hyperv.c
> b/xen/arch/x86/guest/hyperv/hyperv.c
> index da3a8cd85d..a88b9ae6d9 100644
> --- a/xen/arch/x86/guest/hyperv/hyperv.c
> +++ b/xen/arch/x86/guest/hyperv/hyperv.c
> @@ -30,6 +30,7 @@ void *hv_hypercall;
> static struct page_info *hv_hypercall_page;
> DEFINE_PER_CPU_READ_MOSTLY(struct hyperv_pcpu_page, hv_pcpu_input_arg);
> DEFINE_PER_CPU_READ_MOSTLY(unsigned int, hv_vp_index);
> +DEFINE_PER_CPU_READ_MOSTLY(struct hyperv_pcpu_page, hv_vp_assist);
>
> static const struct hypervisor_ops ops;
> const struct hypervisor_ops *__init hyperv_probe(void)
> @@ -125,17 +126,51 @@ static void setup_vp_index(void)
> this_cpu(hv_vp_index) = vp_index_msr;
> }
>
> +static void set_vp_assist(void)
> +{
> + uint64_t val = paddr_to_pfn(this_cpu(hv_vp_assist).maddr);
> +
> + val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) |
I'd recommend using HV_HYP_PAGE_SHIFT instead of
HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT. On the Linux side,
I'm planning to remove that #define and the similar
*_PAGE_ADDRESS_MASK in favor of the newer HV_HYP_PAGE_* values.
There's nothing special about the VP assist page, so using the generic
#defines based on the Hyper-V page size is reasonable.
Michael
> + HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
> +
> + wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
> +}
> +
> +static void setup_vp_assist(void)
> +{
> + struct page_info *pg;
> + void *mapping;
> + unsigned int cpu = smp_processor_id();
> +
> + pg = alloc_domheap_page(NULL, 0);
> + if ( !pg )
> + panic("Failed to allocate vp_assist page for %u\n", cpu);
> +
> + mapping = __map_domain_page_global(pg);
> + if ( !mapping )
> + panic("Failed to map vp_assist page for %u\n", cpu);
> +
> + clear_page(mapping);
> +
> + this_cpu(hv_vp_assist).maddr = page_to_maddr(pg);
> + this_cpu(hv_vp_assist).mapping = mapping;
> +
> + set_vp_assist();
> +}
> +
> static void __init setup(void)
> {
> setup_hypercall_page();
> setup_hypercall_pcpu_arg();
> setup_vp_index();
> + setup_vp_assist();
> }
>
> static void ap_setup(void)
> {
> setup_hypercall_pcpu_arg();
> setup_vp_index();
> + setup_vp_assist();
> }
>
> static const struct hypervisor_ops ops = {
> diff --git a/xen/include/asm-x86/guest/hyperv.h
> b/xen/include/asm-x86/guest/hyperv.h
> index 4b635829f3..917f4e02c2 100644
> --- a/xen/include/asm-x86/guest/hyperv.h
> +++ b/xen/include/asm-x86/guest/hyperv.h
> @@ -71,6 +71,7 @@ struct hyperv_pcpu_page {
> };
> DECLARE_PER_CPU(struct hyperv_pcpu_page, hv_pcpu_input_arg);
> DECLARE_PER_CPU(unsigned int, hv_vp_index);
> +DECLARE_PER_CPU(struct hyperv_pcpu_page, hv_vp_assist);
>
> const struct hypervisor_ops *hyperv_probe(void);
>
> --
> 2.20.1
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