Revert "KVM: x86: zero kvmclock_offset when vcpu0 initializes kvmclock system MSR" (9bac175d) · Commits · 戴 / test

Shifting pvclock_vcpu_time_info.system_time on write to KVM system time MSR is a change of ABI. Probably only 2.6.16 based SLES 10 breaks due to its custom enhancements to kvmclock, but KVM never declared the MSR only for one-shot initialization. (Doc says that only one write is needed.) This reverts commit . And adds a note to the definition of PVCLOCK_COUNTS_FROM_ZERO. Signed-off-by:

Radim Krčmář <rkrcmar@redhat.com> Acked-by:

Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/pvclock-abi.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -41,6 +41,7 @@ struct pvclock_wall_clock {

		#define PVCLOCK_TSC_STABLE_BIT (1 << 0)
		#define PVCLOCK_GUEST_STOPPED (1 << 1)
		/* PVCLOCK_COUNTS_FROM_ZERO broke ABI and can't be used anymore. */
		#define PVCLOCK_COUNTS_FROM_ZERO (1 << 2)
		#endif /* __ASSEMBLY__ */
		#endif /* _ASM_X86_PVCLOCK_ABI_H */

arch/x86/kvm/x86.c

+0 −4

Original line number	Diff line number	Diff line
		@@ -1708,8 +1708,6 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
		vcpu->pvclock_set_guest_stopped_request = false;
		}

		pvclock_flags \|= PVCLOCK_COUNTS_FROM_ZERO;

		/* If the host uses TSC clocksource, then it is stable */
		if (use_master_clock)
		pvclock_flags \|= PVCLOCK_TSC_STABLE_BIT;
		@@ -2007,8 +2005,6 @@ int kvm_set_msr_common(struct kvm_vcpu vcpu, struct msr_data msr_info)
		&vcpu->requests);

		ka->boot_vcpu_runs_old_kvmclock = tmp;

		ka->kvmclock_offset = -get_kernel_ns();
		}

		vcpu->arch.time = data;

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