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 done Thanks, Shannon > > Thanks, > -Christoffer > > . > -- Shannon -- 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
