On Fri, 2019-07-12 at 10:22 +0200, KarimAllah Ahmed wrote: > Valid RAM can live outside kernel control (e.g. using "mem=" command-line > parameter). This memory can still be used as valid guest memory for KVM. So > ensure that we validate that this memory is definitely not "RAM" before > assuming that it is an MMIO region. This patch actually suffers from the same problem pointed out here: https://lkml.org/lkml/2019/7/12/760 .. so I will need to rework them together. > > One way to use memory outside kernel control is: > > 1- Pass 'mem=' in the kernel command-line to limit the amount of memory managed > by the kernel. > 2- Map this physical memory you want to give to the guest with: > mmap("/dev/mem", physical_address_offset, ..) > 3- Use the user-space virtual address as the "userspace_addr" field in > KVM_SET_USER_MEMORY_REGION ioctl. > > One of the limitations of the current /dev/mem for ARM is that it would map > this memory as uncached without this patch: > https://lkml.org/lkml/2019/7/11/684 > > This work is similar to the work done on x86 here: > https://lkml.org/lkml/2019/1/31/933 > > Cc: Marc Zyngier <marc.zyngier@xxxxxxx> > Cc: James Morse <james.morse@xxxxxxx> > Cc: Julien Thierry <julien.thierry@xxxxxxx> > Cc: Suzuki K Pouloze <suzuki.poulose@xxxxxxx> > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > Cc: kvmarm@xxxxxxxxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > Signed-off-by: KarimAllah Ahmed <karahmed@xxxxxxxxx> > --- > virt/kvm/arm/mmu.c | 18 ++++++++++++------ > 1 file changed, 12 insertions(+), 6 deletions(-) > > diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c > index 06180c9..2105134 100644 > --- a/virt/kvm/arm/mmu.c > +++ b/virt/kvm/arm/mmu.c > @@ -8,6 +8,7 @@ > #include <linux/kvm_host.h> > #include <linux/io.h> > #include <linux/hugetlb.h> > +#include <linux/memblock.h> > #include <linux/sched/signal.h> > #include <trace/events/kvm.h> > #include <asm/pgalloc.h> > @@ -89,7 +90,7 @@ static void kvm_flush_dcache_pud(struct kvm *kvm, > > static bool kvm_is_device_pfn(unsigned long pfn) > { > - return !pfn_valid(pfn); > + return !memblock_is_memory(__pfn_to_phys(pfn)); > } > > /** > @@ -949,6 +950,7 @@ static void stage2_unmap_memslot(struct kvm *kvm, > do { > struct vm_area_struct *vma = find_vma(current->mm, hva); > hva_t vm_start, vm_end; > + gpa_t gpa; > > if (!vma || vma->vm_start >= reg_end) > break; > @@ -959,11 +961,14 @@ static void stage2_unmap_memslot(struct kvm *kvm, > vm_start = max(hva, vma->vm_start); > vm_end = min(reg_end, vma->vm_end); > > - if (!(vma->vm_flags & VM_PFNMAP)) { > - gpa_t gpa = addr + (vm_start - memslot->userspace_addr); > - unmap_stage2_range(kvm, gpa, vm_end - vm_start); > - } > hva = vm_end; > + > + if ((vma->vm_flags & VM_PFNMAP) && > + !memblock_is_memory(__pfn_to_phys(vma->vm_pgoff))) > + continue; > + > + gpa = addr + (vm_start - memslot->userspace_addr); > + unmap_stage2_range(kvm, gpa, vm_end - vm_start); > } while (hva < reg_end); > } > > @@ -2329,7 +2334,8 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, > vm_start = max(hva, vma->vm_start); > vm_end = min(reg_end, vma->vm_end); > > - if (vma->vm_flags & VM_PFNMAP) { > + if ((vma->vm_flags & VM_PFNMAP) && > + !memblock_is_memory(__pfn_to_phys(vma->vm_pgoff))) { > gpa_t gpa = mem->guest_phys_addr + > (vm_start - mem->userspace_addr); > phys_addr_t pa; Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Ralf Herbrich Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879 _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
