linux-kernel - Re: [PATCH 3/6 V2] Add ioctl for KVM_GUEST

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Date:	Tue, 1 Nov 2011 16:11:44 -0400
From:	Eric B Munson <emunson@...bm.net>
To:	Anthony Liguori <aliguori@...ibm.com>
Cc:	avi@...hat.com, mingo@...hat.com, x86@...nel.org, hpa@...or.com,
	arnd@...db.de, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	linux-arch@...r.kernel.org, ryanh@...ux.vnet.ibm.com
Subject: Re: [PATCH 3/6 V2] Add ioctl for KVM_GUEST_STOPPED

On Tue, 01 Nov 2011, Anthony Liguori wrote:

> On 10/31/2011 03:07 PM, Eric B Munson wrote:
> >Now that we have a flag that will tell the guest it was suspended, create an
> >interface for that communication using a KVM ioctl.
> >
> >Signed-off-by: Eric B Munson<emunson@...bm.net>
> >---
> >Changes from V1:
> >  Add kvm_set_host_stopped to arch/x86/jvm/x86.c instead of kvmclock.c
> >  Rename KVM_PAUSE_GUEST to KVM_GUEST_PAUSED
> >
> >  arch/x86/include/asm/pvclock.h |    3 +++
> >  arch/x86/kvm/x86.c             |   16 ++++++++++++++++
> >  include/linux/kvm.h            |    2 ++
> >  3 files changed, 21 insertions(+), 0 deletions(-)
> >
> >diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h
> >index 7d3ba41..9312814 100644
> >--- a/arch/x86/include/asm/pvclock.h
> >+++ b/arch/x86/include/asm/pvclock.h
> >@@ -3,6 +3,7 @@
> >
> >  #include<linux/clocksource.h>
> >  #include<asm/pvclock-abi.h>
> >+#include<linux/kvm_host.h>
> >
> >  /* some helper functions for xen and kvm pv clock sources */
> >  cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
> >@@ -13,6 +14,8 @@ void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
> >  			    struct timespec *ts);
> >  void pvclock_resume(void);
> >
> >+void kvm_set_host_stopped(struct kvm_vcpu *vcpu);
> 
> This can't go in pvclock.h.
> 

Will move for V3.

> >+
> >  bool kvm_check_and_clear_host_stopped(int cpu);
> >
> >  /*
> >diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> >index c38efd7..592ac3b 100644
> >--- a/arch/x86/kvm/x86.c
> >+++ b/arch/x86/kvm/x86.c
> >@@ -3295,6 +3295,11 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
> >
> >  		goto out;
> >  	}
> >+	case KVM_GUEST_PAUSED: {
> >+		r = 0;
> >+		kvm_set_host_stopped(vcpu);
> >+		break;
> >+	}
> >  	default:
> >  		r = -EINVAL;
> >  	}
> >@@ -6117,6 +6122,17 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason,
> >  }
> >  EXPORT_SYMBOL_GPL(kvm_task_switch);
> >
> >+/*
> >+ * kvm_set_host_stopped() indicates to the guest kernel that it has been
> >+ * stopped by the hypervisor.  This function will be called from the host only.
> >+ */
> >+void kvm_set_host_stopped(struct kvm_vcpu *vcpu)
> >+{
> >+	struct pvclock_vcpu_time_info *src =&vcpu->arch.hv_clock;
> >+	src->flags |= PVCLOCK_GUEST_STOPPED;
> 
> Shouldn't we throw some sort of error if you're trying to set a flag
> and kvmclock isn't enabled?
> 
> Regards,
> 
> Anthony Liguori
> 

Is kvmclock a compile time only option or something set at runtime?

> >+}
> >+EXPORT_SYMBOL_GPL(kvm_set_host_stopped);
> >+
> >  int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
> >  				  struct kvm_sregs *sregs)
> >  {
> >diff --git a/include/linux/kvm.h b/include/linux/kvm.h
> >index f47fcd3..87cab0d 100644
> >--- a/include/linux/kvm.h
> >+++ b/include/linux/kvm.h
> >@@ -763,6 +763,8 @@ struct kvm_clock_data {
> >  #define KVM_CREATE_SPAPR_TCE	  _IOW(KVMIO,  0xa8, struct kvm_create_spapr_tce)
> >  /* Available with KVM_CAP_RMA */
> >  #define KVM_ALLOCATE_RMA	  _IOR(KVMIO,  0xa9, struct kvm_allocate_rma)
> >+/* VM is being stopped by host */
> >+#define KVM_GUEST_PAUSED	  _IO(KVMIO,   0xaa)
> >
> >  #define KVM_DEV_ASSIGN_ENABLE_IOMMU	(1<<  0)
> >
> 

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