On 26/09/2013 00:31, Paul Mackerras wrote:

On Wed, Sep 25, 2013 at 02:10:27PM +0200, Laurent Dufour wrote:

quoted

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 <redacted>
---
 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.