Re: [Xen-devel] [PATCH v6 11/11] x86/hyperv: setup VP assist page

2020-02-03 Thread Roger Pau Monné 
On Fri, Jan 31, 2020 at 05:49:30PM +, 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 

Reviewed-by: Roger Pau Monné 

Thanks, Roger.

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Re: [Xen-devel] [PATCH v6 11/11] x86/hyperv: setup VP assist page

2020-02-03 Thread Durrant, Paul 
> -Original Message-
> From: Wei Liu  On Behalf Of Wei Liu
> Sent: 31 January 2020 17:50
> To: Xen Development List 
> Cc: Durrant, Paul ; Michael Kelley
> ; Wei Liu ; Wei Liu
> ; Jan Beulich ; Andrew Cooper
> ; Roger Pau Monné 
> Subject: [PATCH v6 11/11] x86/hyperv: setup VP assist page
> 
> VP assist page is rather important as we need to toggle some bits in it
> for efficient nested virtualisation.
> 
> Signed-off-by: Wei Liu 

Reviewed-by: Paul Durrant 

> ---
> v6:
> 1. Use hv_vp_assist_page_msr
> 2. Make code shorter
> 3. Preserve rsvdP fields
> 
> 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  | 37 -
>  xen/arch/x86/guest/hyperv/private.h |  1 +
>  2 files changed, 37 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/x86/guest/hyperv/hyperv.c
> b/xen/arch/x86/guest/hyperv/hyperv.c
> index 6dac3bfceb..75fb329d4d 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_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)
> @@ -155,17 +156,51 @@ static int setup_hypercall_pcpu_arg(void)
>  return 0;
>  }
> 
> +static int setup_vp_assist(void)
> +{
> +union hv_vp_assist_page_msr msr;
> +
> +if ( !this_cpu(hv_vp_assist) )
> +{
> +this_cpu(hv_vp_assist) = alloc_xenheap_page();
> +if ( !this_cpu(hv_vp_assist) )
> +{
> +printk("CPU%u: Failed to allocate vp_assist page\n",
> +   smp_processor_id());
> +return -ENOMEM;
> +}
> +
> +clear_page(this_cpu(hv_vp_assist));
> +}
> +
> +rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.raw);
> +msr.pfn = virt_to_mfn(this_cpu(hv_vp_assist));
> +msr.enabled = 1;
> +wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.raw);
> +
> +return 0;
> +}
> +
>  static void __init setup(void)
>  {
>  setup_hypercall_page();
> 
>  if ( setup_hypercall_pcpu_arg() )
>  panic("Hyper-V 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 )
> +return rc;
> +
> +return setup_vp_assist();
>  }
> 
>  static void __init e820_fixup(struct e820map *e820)
> diff --git a/xen/arch/x86/guest/hyperv/private.h
> b/xen/arch/x86/guest/hyperv/private.h
> index d1765d4f23..956eff831f 100644
> --- a/xen/arch/x86/guest/hyperv/private.h
> +++ b/xen/arch/x86/guest/hyperv/private.h
> @@ -25,6 +25,7 @@
>  #include 
> 
>  DECLARE_PER_CPU(void *, hv_input_page);
> +DECLARE_PER_CPU(void *, hv_vp_assist);
>  DECLARE_PER_CPU(unsigned int, hv_vp_index);
> 
>  #endif /* __XEN_HYPERV_PRIVIATE_H__  */
> --
> 2.20.1


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[Xen-devel] [PATCH v6 11/11] x86/hyperv: setup VP assist page

2020-01-31 Thread Wei Liu 
VP assist page is rather important as we need to toggle some bits in it
for efficient nested virtualisation.

Signed-off-by: Wei Liu 
---
v6:
1. Use hv_vp_assist_page_msr
2. Make code shorter
3. Preserve rsvdP fields

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  | 37 -
 xen/arch/x86/guest/hyperv/private.h |  1 +
 2 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/guest/hyperv/hyperv.c 
b/xen/arch/x86/guest/hyperv/hyperv.c
index 6dac3bfceb..75fb329d4d 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_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)
@@ -155,17 +156,51 @@ static int setup_hypercall_pcpu_arg(void)
 return 0;
 }
 
+static int setup_vp_assist(void)
+{
+union hv_vp_assist_page_msr msr;
+
+if ( !this_cpu(hv_vp_assist) )
+{
+this_cpu(hv_vp_assist) = alloc_xenheap_page();
+if ( !this_cpu(hv_vp_assist) )
+{
+printk("CPU%u: Failed to allocate vp_assist page\n",
+   smp_processor_id());
+return -ENOMEM;
+}
+
+clear_page(this_cpu(hv_vp_assist));
+}
+
+rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.raw);
+msr.pfn = virt_to_mfn(this_cpu(hv_vp_assist));
+msr.enabled = 1;
+wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.raw);
+
+return 0;
+}
+
 static void __init setup(void)
 {
 setup_hypercall_page();
 
 if ( setup_hypercall_pcpu_arg() )
 panic("Hyper-V 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 )
+return rc;
+
+return setup_vp_assist();
 }
 
 static void __init e820_fixup(struct e820map *e820)
diff --git a/xen/arch/x86/guest/hyperv/private.h 
b/xen/arch/x86/guest/hyperv/private.h
index d1765d4f23..956eff831f 100644
--- a/xen/arch/x86/guest/hyperv/private.h
+++ b/xen/arch/x86/guest/hyperv/private.h
@@ -25,6 +25,7 @@
 #include 
 
 DECLARE_PER_CPU(void *, hv_input_page);
+DECLARE_PER_CPU(void *, hv_vp_assist);
 DECLARE_PER_CPU(unsigned int, hv_vp_index);
 
 #endif /* __XEN_HYPERV_PRIVIATE_H__  */
-- 
2.20.1


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