linux-kernel - Re: [PATCH] PPC: KVM: fix VCPU run for HV KVM

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Date:	Sun, 12 Jan 2014 16:44:25 +0100
From:	Alexander Graf <agraf@...e.de>
To:	Alexey Kardashevskiy <aik@...abs.ru>
Cc:	linuxppc-dev@...ts.ozlabs.org, Paul Mackerras <paulus@...ba.org>,
	kvm-ppc@...r.kernel.org,
	"kvm@...r.kernel.org mailing list" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org list" <linux-kernel@...r.kernel.org>,
	"Michael S. Tsirkin" <mst@...hat.com>
Subject: Re: [PATCH] PPC: KVM: fix VCPU run for HV KVM


On 10.01.2014, at 08:21, Alexey Kardashevskiy <aik@...abs.ru> wrote:

> When write to MMIO happens and there is an ioeventfd for that and
> is handled successfully, ioeventfd_write() returns 0 (success) and
> kvmppc_handle_store() returns EMULATE_DONE. Then kvmppc_emulate_mmio()
> converts EMULATE_DONE to RESUME_GUEST_NV and this broke from the loop.
> 
> This adds handling of RESUME_GUEST_NV in kvmppc_vcpu_run_hv().
> 
> Cc: Michael S. Tsirkin <mst@...hat.com>
> Suggested-by: Paul Mackerras <paulus@...ba.org>
> Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
> ---
> 
> This definitely needs a better commit message. Please, help.
> ps. it seems like ioeventfd never worked on ppc64. hm.
> 
> ---
> arch/powerpc/kvm/book3s_hv.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 072287f..24f363f 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -1569,7 +1569,7 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu)
> 				vcpu->arch.fault_dar, vcpu->arch.fault_dsisr);
> 			srcu_read_unlock(&vcpu->kvm->srcu, srcu_idx);
> 		}
> -	} while (r == RESUME_GUEST);
> +	} while ((r == RESUME_GUEST_NV) || (r == RESUME_GUEST));

How about

  while(!(r & RESUME_FLAG_HOST));

That should cover all RESUME_GUEST_XXX cases just fine. Apart from that I agree that we should check for ! FLAG_HOST bit rather than the actual RESUME_GUEST value in all case where we check for it (read: please update all places).


Alex

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