When a Linux VM runs on Hyper-V and hibernates, it must disable the
memory hot-add/remove and balloon up/down capabilities in the hv_balloon
driver.
By default, Hyper-V does not enable the virtual ACPI S4 state for a VM;
on recent Hyper-V hosts, the administrator is able to enable the virtual
ACPI S4 state for a VM, so we hope to use the presence of the virtual ACPI
S4 state as a hint for hv_balloon to disable the aforementioned
capabilities.
The new API will be used by hv_balloon.
Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
---
arch/x86/hyperv/hv_init.c | 7 +++++++
include/asm-generic/mshyperv.h | 2 ++
2 files changed, 9 insertions(+)
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 78e53d9..6735e45 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -7,6 +7,7 @@
* Author : K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
*/
+#include <linux/acpi.h>
#include <linux/efi.h>
#include <linux/types.h>
#include <asm/apic.h>
@@ -453,3 +454,9 @@ bool hv_is_hyperv_initialized(void)
return hypercall_msr.enable;
}
EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);
+
+bool hv_is_hibernation_supported(void)
+{
+ return acpi_sleep_state_supported(ACPI_STATE_S4);
+}
+EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);
diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
index 0becb7d..1cb4001 100644
--- a/include/asm-generic/mshyperv.h
+++ b/include/asm-generic/mshyperv.h
@@ -166,9 +166,11 @@ static inline int cpumask_to_vpset(struct hv_vpset *vpset,
void hyperv_report_panic(struct pt_regs *regs, long err);
void hyperv_report_panic_msg(phys_addr_t pa, size_t size);
bool hv_is_hyperv_initialized(void);
+bool hv_is_hibernation_supported(void);
void hyperv_cleanup(void);
#else /* CONFIG_HYPERV */
static inline bool hv_is_hyperv_initialized(void) { return false; }
+static inline bool hv_is_hibernation_supported(void) { return false; }
static inline void hyperv_cleanup(void) {}
#endif /* CONFIG_HYPERV */
--
1.8.3.1
