On Fri, Sep 26, 2014 at 05:26:00PM +0800, Shannon Zhao wrote: > > > On 2014/9/26 16:44, Christoffer Dall wrote: > > Hi Shannon, > > > > On Fri, Sep 26, 2014 at 01:57:46PM +0800, Shannon Zhao wrote: > >> > >> On 2014/9/26 1:49, Christoffer Dall wrote: > >>> The sgi values calculated in read_set_clear_sgi_pend_reg() and > >>> write_set_clear_sgi_pend_reg() were horribly incorrectly multiplied by 4 > >>> with catastrophic results in that subfunctions ended up overwriting > >>> memory not allocated for the expected purpose. > >>> > >>> This showed up as bugs in kfree() and the kernel complaining a lot of > >>> you turn on memory debugging. > >>> > >>> This addresses: http://marc.info/?l=kvm&m=141164910007868&w=2 > >>> > >>> Reported-by: Shannon Zhao <zhaoshenglong@xxxxxxxxxx> > >>> Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx> > >>> --- > >>> virt/kvm/arm/vgic.c | 4 ++-- > >>> 1 file changed, 2 insertions(+), 2 deletions(-) > >>> > >>> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c > >>> index b6fab0f..8629678 100644 > >>> --- a/virt/kvm/arm/vgic.c > >>> +++ b/virt/kvm/arm/vgic.c > >>> @@ -816,7 +816,7 @@ static bool read_set_clear_sgi_pend_reg(struct kvm_vcpu *vcpu, > >>> { > >>> struct vgic_dist *dist = &vcpu->kvm->arch.vgic; > >>> int sgi; > >>> - int min_sgi = (offset & ~0x3) * 4; > >>> + int min_sgi = (offset & ~0x3); > >>> int max_sgi = min_sgi + 3; > >>> int vcpu_id = vcpu->vcpu_id; > >>> u32 reg = 0; > >>> @@ -837,7 +837,7 @@ static bool write_set_clear_sgi_pend_reg(struct kvm_vcpu *vcpu, > >>> { > >>> struct vgic_dist *dist = &vcpu->kvm->arch.vgic; > >>> int sgi; > >>> - int min_sgi = (offset & ~0x3) * 4; > >>> + int min_sgi = (offset & ~0x3); > >>> int max_sgi = min_sgi + 3; > >>> int vcpu_id = vcpu->vcpu_id; > >>> u32 reg; > >>> > >> Hi Christoffer, > >> > >> I have test this patch for a few hours. The kfree() bug doesn't appear again. > >> But I come to another problem as followed. > >> The test is that start 2 VMs, sleep 10 and do pkill qemu. > >> > >> qemu-system-aar[1207]: unhandled level 1 permission fault (11) at 0xffffc01ed6c200, esr 0x9200000d > >> pgd = ffffffc012986000 > >> [ffffc01ed6c200] *pgd=0000000000000000, *pud=0000000000000000 > >> > >> CPU: 1 PID: 1207 Comm: qemu-system-aar Not tainted 3.17.0-rc4+ #1 > >> task: ffffffc87b072900 ti: ffffffc0129e0000 task.ti: ffffffc0129e0000 > >> PC is at 0x4181a0 > >> LR is at 0x41826c > >> pc : [<00000000004181a0>] lr : [<000000000041826c>] pstate: 80000000 > >> sp : 0000007fcd38ace0 > >> x29: 0000007fcd38ace0 x28: 0000000000000000 > >> x27: 0000000000000000 x26: 0000000000000000 > >> x25: 0000000000000000 x24: 0000000000000000 > >> x23: 0000000000000000 x22: 0000000000000000 > >> x21: 0000000000000000 x20: 0000000000000000 > >> x19: 0000007fcd38b070 x18: 0000007fcd38ab10 > >> x17: 0000007f9bb14480 x16: 00000000009f2370 > >> x15: ffffffffffffffff x14: 0000000000000000 > >> x13: 0000000000000000 x12: 0000000000000268 > >> x11: 00000000115e5520 x10: 0101010101010101 > >> x9 : 0000000000000004 x8 : 0000000000ac7a78 > >> x7 : 0000000000000000 x6 : 000000000000003f > >> x5 : 0000000000000040 x4 : 0000000000000000 > >> x3 : 0000000000000030 x2 : 0000000000000001 > >> x1 : ffffffc01ed6c200 x0 : ffffffc01ed6c200 > >> > > Hmmm, I just ran a similar loop with a number of tests in the VM for a > > few hours and I didn't see this error. > Yeah, it really need to run longer. > After running about one hour this problem first appears and after running > about 4 hours it second appears. > > > > In any case, this patch should still be merged, but we should try to > > reproduce your setup. > Your patch really solves the kfree() bug. I'll add tested-by line. > > > > What is your command line, exact QEMU version, the file system you use, > > and the guest kernel you are running? > My test script is as followed. QEMU version is v2.1.0 release. > The fs is linaro-image-lamp-genericarmv8-20140727-701.rootfs.tar.gz. > Host kernel is based on marc's branch "kvmtool-vgic-dyn" with your patch > "Fix set_clear_sgi_pend_reg offset". > Guest kernel is 3.16 release. > > while true > do > qemu-system-aarch64 \ > -enable-kvm -smp 4 \ > -kernel Image \ > -m 512 -machine virt,kernel_irqchip=on \ > -initrd guestfs.cpio.gz \ > -cpu host \ > -chardev pty,id=pty0,mux=on -monitor chardev:pty0 \ > -serial chardev:pty0 -daemonize \ > -vnc 0.0.0.0:0 \ > -append "rdinit=/sbin/init console=ttyAMA0 mem=512M root=/dev/ram earlyprintk=pl011,0x9000000 rw" & > > qemu-system-aarch64 \ > -enable-kvm -smp 4 \ > -kernel Image \ > -m 512 -machine virt,kernel_irqchip=on \ > -initrd guestfs.cpio.gz \ > -cpu host \ > -chardev pty,id=pty0,mux=on -monitor chardev:pty0 \ > -serial chardev:pty0 -daemonize \ > -vnc 0.0.0.0:1 \ > -append "rdinit=/sbin/init console=ttyAMA0 mem=512M root=/dev/ram earlyprintk=pl011,0x9000000 rw" & > sleep 5 > pkill qemu ok, I'll try to reproduce. Thanks, -Christoffer -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
