424c32f1aa
This patch removes one padding byte and transform it into a flags field. New versions of guests using pvclock will query these flags upon each read. Flags, however, will only be interpreted when the guest decides to. It uses the pvclock_valid_flags function to signal that a specific set of flags should be taken into consideration. Which flags are valid are usually devised via HV negotiation. Signed-off-by: Glauber Costa <glommer@redhat.com> CC: Jeremy Fitzhardinge <jeremy@goop.org> Acked-by: Zachary Amsden <zamsden@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
43 lines
1.3 KiB
C
43 lines
1.3 KiB
C
#ifndef _ASM_X86_PVCLOCK_ABI_H
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#define _ASM_X86_PVCLOCK_ABI_H
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#ifndef __ASSEMBLY__
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/*
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* These structs MUST NOT be changed.
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* They are the ABI between hypervisor and guest OS.
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* Both Xen and KVM are using this.
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*
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* pvclock_vcpu_time_info holds the system time and the tsc timestamp
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* of the last update. So the guest can use the tsc delta to get a
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* more precise system time. There is one per virtual cpu.
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*
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* pvclock_wall_clock references the point in time when the system
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* time was zero (usually boot time), thus the guest calculates the
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* current wall clock by adding the system time.
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*
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* Protocol for the "version" fields is: hypervisor raises it (making
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* it uneven) before it starts updating the fields and raises it again
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* (making it even) when it is done. Thus the guest can make sure the
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* time values it got are consistent by checking the version before
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* and after reading them.
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*/
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struct pvclock_vcpu_time_info {
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u32 version;
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u32 pad0;
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u64 tsc_timestamp;
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u64 system_time;
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u32 tsc_to_system_mul;
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s8 tsc_shift;
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u8 flags;
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u8 pad[2];
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} __attribute__((__packed__)); /* 32 bytes */
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struct pvclock_wall_clock {
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u32 version;
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u32 sec;
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u32 nsec;
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} __attribute__((__packed__));
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#endif /* __ASSEMBLY__ */
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#endif /* _ASM_X86_PVCLOCK_ABI_H */
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