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![Dexuan Cui](/assets/img/avatar_default.png)
The API will be used by the hv_balloon and hv_vmbus drivers. Balloon up/down and hot-add of memory must not be active if the user wants the Linux VM to support hibernation, because they are incompatible with hibernation according to Hyper-V team, e.g. upon suspend the balloon VSP doesn't save any info about the ballooned-out pages (if any); so, after Linux resumes, Linux balloon VSC expects that the VSP will return the pages if Linux is under memory pressure, but the VSP will never do that, since the VSP thinks it never stole the pages from the VM. So, if the user wants Linux VM to support hibernation, Linux must forbid balloon up/down and hot-add, and the only functionality of the balloon VSC driver is reporting the VM's memory pressure to the host. Ideally, when Linux detects that the user wants it to support hibernation, the balloon VSC should tell the VSP that it does not support ballooning and hot-add. However, the current version of the VSP requires the VSC should support these capabilities, otherwise the capability negotiation fails and the VSC can not load at all, so with the later changes to the VSC driver, Linux VM still reports to the VSP that the VSC supports these capabilities, but the VSC ignores the VSP's requests of balloon up/down and hot add, and reports an error to the VSP, when applicable. BTW, in the future the balloon VSP driver will allow the VSC to not support the capabilities of balloon up/down and hot add. The ACPI S4 state is not a must for hibernation to work, because Linux is able to hibernate as long as the system can shut down. However in practice we decide to artificially use the presence of the virtual ACPI S4 state as an indicator of the user's intent of using hibernation, because Linux VM must find a way to know if the user wants to use the hibernation feature or not. By default, Hyper-V does not enable the virtual ACPI S4 state; on recent Hyper-V hosts (e.g. RS5, 19H1), the administrator is able to enable the state for a VM by WMI commands. Once all the vmbus and VSC patches for the hibernation feature are accepted, an extra patch will be submitted to forbid hibernation if the virtual ACPI S4 state is absent, i.e. hv_is_hibernation_supported() is false. Signed-off-by: Dexuan Cui <decui@microsoft.com> Reviewed-by: Michael Kelley <mikelley@microsoft.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
183 lines
5.4 KiB
C
183 lines
5.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Linux-specific definitions for managing interactions with Microsoft's
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* Hyper-V hypervisor. The definitions in this file are architecture
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* independent. See arch/<arch>/include/asm/mshyperv.h for definitions
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* that are specific to architecture <arch>.
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*
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* Definitions that are specified in the Hyper-V Top Level Functional
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* Spec (TLFS) should not go in this file, but should instead go in
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* hyperv-tlfs.h.
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*
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* Copyright (C) 2019, Microsoft, Inc.
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*
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* Author : Michael Kelley <mikelley@microsoft.com>
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*/
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#ifndef _ASM_GENERIC_MSHYPERV_H
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#define _ASM_GENERIC_MSHYPERV_H
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#include <linux/types.h>
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#include <linux/atomic.h>
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#include <linux/bitops.h>
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#include <linux/cpumask.h>
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#include <asm/ptrace.h>
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#include <asm/hyperv-tlfs.h>
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struct ms_hyperv_info {
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u32 features;
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u32 misc_features;
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u32 hints;
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u32 nested_features;
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u32 max_vp_index;
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u32 max_lp_index;
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};
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extern struct ms_hyperv_info ms_hyperv;
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extern u64 hv_do_hypercall(u64 control, void *inputaddr, void *outputaddr);
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extern u64 hv_do_fast_hypercall8(u16 control, u64 input8);
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/* Generate the guest OS identifier as described in the Hyper-V TLFS */
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static inline __u64 generate_guest_id(__u64 d_info1, __u64 kernel_version,
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__u64 d_info2)
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{
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__u64 guest_id = 0;
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guest_id = (((__u64)HV_LINUX_VENDOR_ID) << 48);
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guest_id |= (d_info1 << 48);
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guest_id |= (kernel_version << 16);
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guest_id |= d_info2;
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return guest_id;
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}
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/* Free the message slot and signal end-of-message if required */
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static inline void vmbus_signal_eom(struct hv_message *msg, u32 old_msg_type)
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{
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/*
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* On crash we're reading some other CPU's message page and we need
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* to be careful: this other CPU may already had cleared the header
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* and the host may already had delivered some other message there.
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* In case we blindly write msg->header.message_type we're going
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* to lose it. We can still lose a message of the same type but
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* we count on the fact that there can only be one
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* CHANNELMSG_UNLOAD_RESPONSE and we don't care about other messages
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* on crash.
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*/
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if (cmpxchg(&msg->header.message_type, old_msg_type,
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HVMSG_NONE) != old_msg_type)
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return;
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/*
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* The cmxchg() above does an implicit memory barrier to
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* ensure the write to MessageType (ie set to
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* HVMSG_NONE) happens before we read the
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* MessagePending and EOMing. Otherwise, the EOMing
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* will not deliver any more messages since there is
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* no empty slot
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*/
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if (msg->header.message_flags.msg_pending) {
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/*
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* This will cause message queue rescan to
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* possibly deliver another msg from the
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* hypervisor
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*/
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hv_signal_eom();
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}
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}
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void hv_setup_vmbus_irq(void (*handler)(void));
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void hv_remove_vmbus_irq(void);
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void hv_enable_vmbus_irq(void);
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void hv_disable_vmbus_irq(void);
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void hv_setup_kexec_handler(void (*handler)(void));
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void hv_remove_kexec_handler(void);
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void hv_setup_crash_handler(void (*handler)(struct pt_regs *regs));
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void hv_remove_crash_handler(void);
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#if IS_ENABLED(CONFIG_HYPERV)
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/*
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* Hypervisor's notion of virtual processor ID is different from
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* Linux' notion of CPU ID. This information can only be retrieved
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* in the context of the calling CPU. Setup a map for easy access
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* to this information.
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*/
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extern u32 *hv_vp_index;
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extern u32 hv_max_vp_index;
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/* Sentinel value for an uninitialized entry in hv_vp_index array */
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#define VP_INVAL U32_MAX
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/**
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* hv_cpu_number_to_vp_number() - Map CPU to VP.
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* @cpu_number: CPU number in Linux terms
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*
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* This function returns the mapping between the Linux processor
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* number and the hypervisor's virtual processor number, useful
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* in making hypercalls and such that talk about specific
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* processors.
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*
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* Return: Virtual processor number in Hyper-V terms
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*/
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static inline int hv_cpu_number_to_vp_number(int cpu_number)
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{
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return hv_vp_index[cpu_number];
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}
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static inline int cpumask_to_vpset(struct hv_vpset *vpset,
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const struct cpumask *cpus)
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{
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int cpu, vcpu, vcpu_bank, vcpu_offset, nr_bank = 1;
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/* valid_bank_mask can represent up to 64 banks */
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if (hv_max_vp_index / 64 >= 64)
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return 0;
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/*
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* Clear all banks up to the maximum possible bank as hv_tlb_flush_ex
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* structs are not cleared between calls, we risk flushing unneeded
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* vCPUs otherwise.
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*/
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for (vcpu_bank = 0; vcpu_bank <= hv_max_vp_index / 64; vcpu_bank++)
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vpset->bank_contents[vcpu_bank] = 0;
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/*
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* Some banks may end up being empty but this is acceptable.
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*/
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for_each_cpu(cpu, cpus) {
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vcpu = hv_cpu_number_to_vp_number(cpu);
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if (vcpu == VP_INVAL)
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return -1;
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vcpu_bank = vcpu / 64;
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vcpu_offset = vcpu % 64;
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__set_bit(vcpu_offset, (unsigned long *)
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&vpset->bank_contents[vcpu_bank]);
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if (vcpu_bank >= nr_bank)
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nr_bank = vcpu_bank + 1;
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}
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vpset->valid_bank_mask = GENMASK_ULL(nr_bank - 1, 0);
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return nr_bank;
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}
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void hyperv_report_panic(struct pt_regs *regs, long err);
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void hyperv_report_panic_msg(phys_addr_t pa, size_t size);
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bool hv_is_hyperv_initialized(void);
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bool hv_is_hibernation_supported(void);
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void hyperv_cleanup(void);
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void hv_setup_sched_clock(void *sched_clock);
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#else /* CONFIG_HYPERV */
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static inline bool hv_is_hyperv_initialized(void) { return false; }
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static inline bool hv_is_hibernation_supported(void) { return false; }
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static inline void hyperv_cleanup(void) {}
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#endif /* CONFIG_HYPERV */
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#if IS_ENABLED(CONFIG_HYPERV)
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extern int hv_setup_stimer0_irq(int *irq, int *vector, void (*handler)(void));
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extern void hv_remove_stimer0_irq(int irq);
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#endif
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#endif
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