On 05/14/15 12:30, Christoffer Dall wrote: > On Wed, May 13, 2015 at 01:31:51PM +0200, Andrew Jones wrote: >> Introduce a new memory region flag, KVM_MEM_UNCACHED, which is >> needed by ARM. This flag informs KVM that the given memory region >> is typically mapped by the guest as non-cacheable. KVM for ARM >> then ensures that that memory is indeed mapped non-cacheable by >> the guest, and also remaps that region as non-cacheable for >> userspace, allowing them both to maintain a coherent view. >> >> Changes since v1: >> 1) don't pin pages [Paolo] >> 2) ensure the guest maps the memory non-cacheable [me] >> 3) clean up memslot flag documentation [Christoffer] >> changes 1 and 2 effectively redesigned/rewrote v1. Find v1 here >> http://www.spinics.net/lists/kvm-arm/msg14022.html >> >> The QEMU series for v1 hasn't really changed. Only the linux >> header hack needed to bump KVM_CAP_UNCACHED_MEM from 107 to >> 116. Find the series here >> http://www.spinics.net/lists/kvm-arm/msg14026.html >> >> Testing: >> This series still needs lots of testing, but I thought I'd >> kick it to the list early, as there's been recent interest >> in solving this problem, and I'd like to get test results >> and opinions on this approach from others sooner than later. >> I've tested with AAVMF (UEFI for AArch64 mach-virt guests). >> AAVMF has a kludge in it to avoid the coherency problem. > > How does the 'kludge' work? https://github.com/tianocore/edk2/commit/f9a8be42 (It's probably worth looking at the documentation in the first hunk too, under the commit message.) Thanks Laszlo > >> I've tested both with and without that kludge active. Both >> worked for me (almost). Sometimes with the non-kludged >> version I was still able to see a bit of corruption in >> grub's output after edk2 loaded it - not much, and not always, >> but something. > > Remind me, this is a VGA framebuffer corruption with a PCI-plugged VGA > card? > > Thanks, > -Christoffer > >> Anyway, it's quite frustrating, as I'm not sure >> what I'm missing... >> >> This series applies to Linus' 110bc76729d4, but I tested with >> a version backported to the current RHELSA kernel. >> >> Thanks for reviews and testing! >> >> drew >> >> >> Andrew Jones (3): >> arm/arm64: pageattr: add set_memory_nc >> KVM: promote KVM_MEMSLOT_INCOHERENT to uapi >> arm/arm64: KVM: implement 'uncached' mem coherency >> >> Documentation/virtual/kvm/api.txt | 20 ++++++++++++------ >> arch/arm/include/asm/cacheflush.h | 1 + >> arch/arm/include/asm/kvm_mmu.h | 5 ++++- >> arch/arm/include/asm/pgtable-3level.h | 1 + >> arch/arm/include/asm/pgtable.h | 1 + >> arch/arm/include/uapi/asm/kvm.h | 1 + >> arch/arm/kvm/arm.c | 1 + >> arch/arm/kvm/mmu.c | 39 ++++++++++++++++++++++------------- >> arch/arm/mm/pageattr.c | 7 +++++++ >> arch/arm64/include/asm/cacheflush.h | 1 + >> arch/arm64/include/asm/kvm_mmu.h | 5 ++++- >> arch/arm64/include/asm/memory.h | 1 + >> arch/arm64/include/asm/pgtable.h | 1 + >> arch/arm64/include/uapi/asm/kvm.h | 1 + >> arch/arm64/mm/pageattr.c | 8 +++++++ >> include/linux/kvm_host.h | 1 - >> include/uapi/linux/kvm.h | 2 ++ >> virt/kvm/kvm_main.c | 7 ++++++- >> 18 files changed, 79 insertions(+), 24 deletions(-) >> >> -- >> 2.1.0 >> _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
