On Thu, Jun 18, 2020 at 03:31:06PM +0200, Laurent Dufour wrote: > Le 18/06/2020 à 11:19, Ram Pai a écrit : > > .snip.. > >************************************************************************ > > 1. States of a GFN > > --------------- > > The GFN can be in one of the following states. > >diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c ...snip... > >index 803940d..3448459 100644 > >--- a/arch/powerpc/kvm/book3s_64_mmu_radix.c > >+++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c > >@@ -1100,7 +1100,7 @@ void kvmppc_radix_flush_memslot(struct kvm *kvm, > > unsigned int shift; > > if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START) > >- kvmppc_uvmem_drop_pages(memslot, kvm, true); > >+ kvmppc_uvmem_drop_pages(memslot, kvm, true, false); > > When reviewing the v1 of this series, I asked you the question about > the fact that the call here is made with purge_gfn = false. Your > answer was: > > >This function does not know, under what context it is called. Since > >its job is to just flush the memslot, it cannot assume anything > >about purging the pages in the memslot. > > Indeed in the case of the memory hotplug operation, this function is > called to wipe the page from the secure device in the case the pages > are secured. In that case the purge is required. Indeed, I checked > the other call to kvmppc_radix_flush_memslot() in > kvmppc_core_flush_memslot_hv() and I cannot see why in that case too > purge_gfn should be false, especially when the memslot is reused as > detailed in __kvm_set_memory_region() around the call to > kvm_arch_flush_shadow_memslot(). > > I'm sorry to not have ask this earlier, but could you please elaborate on this? You are right. kvmppc_radix_flush_memslot() is getting called everytime with the intention of disassociating the memslot from that VM. Which implies, the memslot is intended to be deleted and possibly reused. I should be calling kvmppc_uvmem_drop_pages() with purge_gfn=true, here aswell. I expect some form of problem showing up in memhot-plug/unplug path. RP
