2019-07-09 05:30:27

by Dexuan Cui

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

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 <[email protected]>
---
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

2019-07-31 00:14:44

by Michael Kelley (LINUX)

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

From: Dexuan Cui <[email protected]> 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 <[email protected]>
> ---
> 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 <[email protected]>