From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Dufour Date: Tue, 25 Feb 2014 16:00:52 +0000 Subject: Re: [PATCH] PPC: KVM: Introduce hypervisor call H_GET_TCE Message-Id: <530CBE34.4000004@linux.vnet.ibm.com> List-Id: References: <20140221153110.8190.6271.stgit@nimbus> <75FB1EEB-910A-49A9-A4CC-0A2E5403C54C@suse.de> In-Reply-To: <75FB1EEB-910A-49A9-A4CC-0A2E5403C54C@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Alexander Graf Cc: Gleb Natapov , Paolo Bonzini , Paul Mackerras , Ben Herrenschmidt , linuxppc-dev@lists.ozlabs.org, kvm-ppc , "kvm@vger.kernel.org mailing list" On 21/02/2014 16:57, Alexander Graf wrote: > > On 21.02.2014, at 16:31, Laurent Dufour wrote: > >> This fix introduces the H_GET_TCE hypervisor call which is basically the >> reverse of H_PUT_TCE, as defined in the Power Architecture Platform >> Requirements (PAPR). >> >> The hcall H_GET_TCE is required by the kdump kernel which is calling it to >> retrieve the TCE set up by the panicing kernel. >> >> Signed-off-by: Laurent Dufour > > Thanks, applied to kvm-ppc-queue. Btw, why exactly are we using struct page pointers and alloc_page rather than __get_free_page() and simple page start pointers? FWIW, I'm not so familiar with that part of code, it seems that this is due to the page fault handler (kvm_spapr_tce_fault) which is part of the mmap file operation handlers associated to the fd returned by kvm_vm_ioctl_create_spapr_tce. Underlying vma's operation requires the page fault handler to return a struct page value in the vm_fault structure. Cheers, Laurent.