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

Dexuan Cui
2019-07-09T05:29:37Z

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