RE: [PATCH 1/7] x86/hyper-v: Suspend/resume the hypercall page for hibernation

[Michael Kelley]

From: Dexuan Cui  Sent: Monday, July 8, 2019 10:29 PM
> 
> This is needed for hibernation, e.g. when we resume the old kernel, we need
> to disable the "current" kernel's hypercall page and then resume the old
> kernel's.
> 
> Signed-off-by: Dexuan Cui 
> ---
>  arch/x86/hyperv/hv_init.c | 34 ++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index 0e033ef..3005871 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -20,6 +20,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>  #include 
> 
>  void *hv_hypercall_pg;
> @@ -214,6 +215,34 @@ static int __init hv_pci_init(void)
>   return 1;
>  }
> 
> +static int hv_suspend(void)
> +{
> + union hv_x64_msr_hypercall_contents hypercall_msr;
> +
> + /* Reset the hypercall page */
> + rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> + hypercall_msr.enable = 0;
> + wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> +
> + return 0;
> +}
> +
> +static void hv_resume(void)
> +{
> + union hv_x64_msr_hypercall_contents hypercall_msr;
> +
> + /* Re-enable the hypercall page */
> + rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> + hypercall_msr.enable = 1;
> + hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
> + wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
> +}
> +
> +static struct syscore_ops hv_syscore_ops = {
> + .suspend = hv_suspend,
> + .resume = hv_resume,
> +};
> +
>  /*
>   * This function is to be invoked early in the boot sequence after the
>   * hypervisor has been detected.
> @@ -294,6 +323,9 @@ void __init hyperv_init(void)
> 
>   /* Register Hyper-V specific clocksource */
>   hv_init_clocksource();
> +
> + register_syscore_ops(_syscore_ops);
> +
>   return;
> 
>  remove_cpuhp_state:
> @@ -313,6 +345,8 @@ void hyperv_cleanup(void)
>  {
>   union hv_x64_msr_hypercall_contents hypercall_msr;
> 
> + unregister_syscore_ops(_syscore_ops);
> +
>   /* Reset our OS id */
>   wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
> 
> --
> 1.8.3.1

Reviewed-by: Michael Kelley 

[PATCH 1/7] x86/hyper-v: Suspend/resume the hypercall page for hibernation

[Dexuan Cui]

This is needed for hibernation, e.g. when we resume the old kernel, we need
to disable the "current" kernel's hypercall page and then resume the old
kernel's.

Signed-off-by: Dexuan Cui 
---
 arch/x86/hyperv/hv_init.c | 34 ++
 1 file changed, 34 insertions(+)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 0e033ef..3005871 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -20,6 +20,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 
 void *hv_hypercall_pg;
@@ -214,6 +215,34 @@ static int __init hv_pci_init(void)
return 1;
 }
 
+static int hv_suspend(void)
+{
+   union hv_x64_msr_hypercall_contents hypercall_msr;
+
+   /* Reset the hypercall page */
+   rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+   hypercall_msr.enable = 0;
+   wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+
+   return 0;
+}
+
+static void hv_resume(void)
+{
+   union hv_x64_msr_hypercall_contents hypercall_msr;
+
+   /* Re-enable the hypercall page */
+   rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+   hypercall_msr.enable = 1;
+   hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
+   wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+}
+
+static struct syscore_ops hv_syscore_ops = {
+   .suspend = hv_suspend,
+   .resume = hv_resume,
+};
+
 /*
  * This function is to be invoked early in the boot sequence after the
  * hypervisor has been detected.
@@ -294,6 +323,9 @@ void __init hyperv_init(void)
 
/* Register Hyper-V specific clocksource */
hv_init_clocksource();
+
+   register_syscore_ops(_syscore_ops);
+
return;
 
 remove_cpuhp_state:
@@ -313,6 +345,8 @@ void hyperv_cleanup(void)
 {
union hv_x64_msr_hypercall_contents hypercall_msr;
 
+   unregister_syscore_ops(_syscore_ops);
+
/* Reset our OS id */
wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 
-- 
1.8.3.1