| Message ID | 20130925121027.29504.19269.stgit@nimbus (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Wed, 25 Sep 2013 14:10:27 +0200 Laurent Dufour <ldufour@linux.vnet.ibm.com> wrote: > Follow-up to Anton's H_SET_MODE patch, the host should be taken aware of > guest endianess change. > > The hcall H_SET_MODE is processed in kvm then in the host. > > Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> Tested-by: Greg Kurz <gkurz@linux.vnet.ibm.com> > --- > arch/powerpc/kvm/book3s_hv.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 998cad3..4a47c74 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -599,6 +599,14 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu) > kvmppc_get_gpr(vcpu, 5), > kvmppc_get_gpr(vcpu, 6), > kvmppc_get_gpr(vcpu, 7)); > + /* > + * If the hcall succeeded, we propagate it to the host. > + * This way, it will be aware of the endianess's change too. > + * The assumption is made that the hcall will succeed in the > + * host. Hmmm... Not sure the last sentence is appropriate from a kernel perspective: it is up to the userland code to remain consistent with this endianess change. > + */ > + if (ret == H_SUCCESS) > + return RESUME_HOST; > break; > > case H_XIRR: > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev >
On Wed, Sep 25, 2013 at 02:10:27PM +0200, Laurent Dufour wrote: > Follow-up to Anton's H_SET_MODE patch, the host should be taken aware of > guest endianess change. > > The hcall H_SET_MODE is processed in kvm then in the host. > > Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> > --- > arch/powerpc/kvm/book3s_hv.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c > index 998cad3..4a47c74 100644 > --- a/arch/powerpc/kvm/book3s_hv.c > +++ b/arch/powerpc/kvm/book3s_hv.c > @@ -599,6 +599,14 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu) > kvmppc_get_gpr(vcpu, 5), > kvmppc_get_gpr(vcpu, 6), > kvmppc_get_gpr(vcpu, 7)); > + /* > + * If the hcall succeeded, we propagate it to the host. > + * This way, it will be aware of the endianess's change too. > + * The assumption is made that the hcall will succeed in the > + * host. > + */ > + if (ret == H_SUCCESS) > + return RESUME_HOST; > break; The problem with this is that H_SET_MODE isn't just used for setting endianness; it also does breakpoint setting (DAWR/X and CIABR), which might happen very frequently, so we don't want them being punted up to userspace. Paul.
On 26/09/2013 00:31, Paul Mackerras wrote: > On Wed, Sep 25, 2013 at 02:10:27PM +0200, Laurent Dufour wrote: >> Follow-up to Anton's H_SET_MODE patch, the host should be taken aware of >> guest endianess change. >> >> The hcall H_SET_MODE is processed in kvm then in the host. >> >> Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> >> --- >> arch/powerpc/kvm/book3s_hv.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c >> index 998cad3..4a47c74 100644 >> --- a/arch/powerpc/kvm/book3s_hv.c >> +++ b/arch/powerpc/kvm/book3s_hv.c >> @@ -599,6 +599,14 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu) >> kvmppc_get_gpr(vcpu, 5), >> kvmppc_get_gpr(vcpu, 6), >> kvmppc_get_gpr(vcpu, 7)); >> + /* >> + * If the hcall succeeded, we propagate it to the host. >> + * This way, it will be aware of the endianess's change too. >> + * The assumption is made that the hcall will succeed in the >> + * host. >> + */ >> + if (ret == H_SUCCESS) >> + return RESUME_HOST; >> break; > > The problem with this is that H_SET_MODE isn't just used for setting > endianness; it also does breakpoint setting (DAWR/X and CIABR), which > might happen very frequently, so we don't want them being punted up to > userspace. > > Paul. Hi Paul, My mistake, the patch was based on a too old kernel missing yours and Michael's latest patches on H_SET_MODE handling. I'll propose a new one asap. Thanks, Laurent.
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 998cad3..4a47c74 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -599,6 +599,14 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu) kvmppc_get_gpr(vcpu, 5), kvmppc_get_gpr(vcpu, 6), kvmppc_get_gpr(vcpu, 7)); + /* + * If the hcall succeeded, we propagate it to the host. + * This way, it will be aware of the endianess's change too. + * The assumption is made that the hcall will succeed in the + * host. + */ + if (ret == H_SUCCESS) + return RESUME_HOST; break; case H_XIRR:
Follow-up to Anton's H_SET_MODE patch, the host should be taken aware of guest endianess change. The hcall H_SET_MODE is processed in kvm then in the host. Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> --- arch/powerpc/kvm/book3s_hv.c | 8 ++++++++ 1 file changed, 8 insertions(+)