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

Michael Kelley
2019-07-30T22:19:31Z

From: Dexuan Cui <decui@microsoft.com> 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 <decui@microsoft.com>
> ---
> 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 <linux/hyperv.h>
> #include <linux/slab.h>
> #include <linux/cpuhotplug.h>
> +#include <linux/syscore_ops.h>
> #include <clocksource/hyperv_timer.h>
>
> 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(&hv_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(&hv_syscore_ops);
> +
> /* Reset our OS id */
> wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
>
> --
> 1.8.3.1

Reviewed-by: Michael Kelley <mikelley@microsoft.com>