> -----Original Message----- > From: Catalin Marinas <catalin.marinas@xxxxxxx> > Sent: Tuesday, December 5, 2023 11:41 AM > To: Marc Zyngier <maz@xxxxxxxxxx> > Cc: ankita@xxxxxxxxxx; Shameerali Kolothum Thodi > <shameerali.kolothum.thodi@xxxxxxxxxx>; jgg@xxxxxxxxxx; > oliver.upton@xxxxxxxxx; suzuki.poulose@xxxxxxx; yuzenghui > <yuzenghui@xxxxxxxxxx>; will@xxxxxxxxxx; ardb@xxxxxxxxxx; akpm@linux- > foundation.org; gshan@xxxxxxxxxx; aniketa@xxxxxxxxxx; cjia@xxxxxxxxxx; > kwankhede@xxxxxxxxxx; targupta@xxxxxxxxxx; vsethi@xxxxxxxxxx; > acurrid@xxxxxxxxxx; apopple@xxxxxxxxxx; jhubbard@xxxxxxxxxx; > danw@xxxxxxxxxx; mochs@xxxxxxxxxx; kvmarm@xxxxxxxxxxxxxxx; > kvm@xxxxxxxxxxxxxxx; lpieralisi@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > Subject: Re: [PATCH v2 1/1] KVM: arm64: allow the VM to select DEVICE_* > and NORMAL_NC for IO memory > > + Lorenzo, he really needs to be on this thread. > > On Tue, Dec 05, 2023 at 09:21:28AM +0000, Marc Zyngier wrote: > > On Tue, 05 Dec 2023 03:30:15 +0000, > > <ankita@xxxxxxxxxx> wrote: > > > From: Ankit Agrawal <ankita@xxxxxxxxxx> > > > > > > Currently, KVM for ARM64 maps at stage 2 memory that is considered > device > > > (i.e. it is not RAM) with DEVICE_nGnRE memory attributes; this setting > > > overrides (as per the ARM architecture [1]) any device MMIO mapping > > > present at stage 1, resulting in a set-up whereby a guest operating > > > system cannot determine device MMIO mapping memory attributes on > its > > > own but it is always overridden by the KVM stage 2 default. > [...] > > Despite the considerable increase in the commit message length, a > > number of questions are left unanswered: > > > > - Shameer reported a regression on non-FWB systems, breaking device > > assignment: > > > > > https://lore.kernel.org/all/af13ed63dc9a4f26a6c958ebfa77d78a@xxxxxxxxx > m/ > > This referred to the first patch in the old series which was trying to > make the Stage 2 cacheable based on the vma attributes. That patch has > been dropped for now. It would be good if Shameer confirms this was the > problem. > Yes, that was related to the first patch. We will soon test this on both FWB and non-FWB platforms and report back. Thanks, Shameer
