On Thu, 19 Mar 2020 19:55:10 -0300
Fabiano Rosas <faro...@linux.ibm.com> wrote:
> kvmppc_uvmem_init checks for Ultravisor support and returns early if
> it is not present. Calling kvmppc_uvmem_free at module exit will cause
> an Oops:
>
> $ modprobe -r kvm-hv
>
> Oops: Kernel access of bad area, sig: 11 [#1]
> <snip>
> NIP: c000000000789e90 LR: c000000000789e8c CTR: c000000000401030
> REGS: c000003fa7bab9a0 TRAP: 0300 Not tainted
> (5.6.0-rc6-00033-g6c90b86a745a-dirty)
> MSR: 9000000000009033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 24002282 XER:
> 00000000
> CFAR: c000000000dae880 DAR: 0000000000000008 DSISR: 40000000 IRQMASK: 1
> GPR00: c000000000789e8c c000003fa7babc30 c0000000016fe500 0000000000000000
> GPR04: 0000000000000000 0000000000000006 0000000000000000 c000003faf205c00
> GPR08: 0000000000000000 0000000000000001 000000008000002d c00800000ddde140
> GPR12: c000000000401030 c000003ffffd9080 0000000000000001 0000000000000000
> GPR16: 0000000000000000 0000000000000000 000000013aad0074 000000013aaac978
> GPR20: 000000013aad0070 0000000000000000 00007fffd1b37158 0000000000000000
> GPR24: 000000014fef0d58 0000000000000000 000000014fef0cf0 0000000000000001
> GPR28: 0000000000000000 0000000000000000 c0000000018b2a60 0000000000000000
> NIP [c000000000789e90] percpu_ref_kill_and_confirm+0x40/0x170
> LR [c000000000789e8c] percpu_ref_kill_and_confirm+0x3c/0x170
> Call Trace:
> [c000003fa7babc30] [c000003faf2064d4] 0xc000003faf2064d4 (unreliable)
> [c000003fa7babcb0] [c000000000400e8c] dev_pagemap_kill+0x6c/0x80
> [c000003fa7babcd0] [c000000000401064] memunmap_pages+0x34/0x2f0
> [c000003fa7babd50] [c00800000dddd548] kvmppc_uvmem_free+0x30/0x80 [kvm_hv]
> [c000003fa7babd80] [c00800000ddcef18] kvmppc_book3s_exit_hv+0x20/0x78
> [kvm_hv]
> [c000003fa7babda0] [c0000000002084d0] sys_delete_module+0x1d0/0x2c0
> [c000003fa7babe20] [c00000000000b9d0] system_call+0x5c/0x68
> Instruction dump:
> 3fc2001b fb81ffe0 fba1ffe8 fbe1fff8 7c7f1b78 7c9c2378 3bde4560 7fc3f378
> f8010010 f821ff81 486249a1 60000000 <e93f0008> 7c7d1b78 712a0002 40820084
> ---[ end trace 5774ef4dc2c98279 ]---
>
> So this patch checks if kvmppc_uvmem_init actually allocated anything
> before running kvmppc_uvmem_free.
>
> Fixes: ca9f4942670c ("KVM: PPC: Book3S HV: Support for running secure guests")
> Reported-by: Greg Kurz <gr...@kaod.org>
> Signed-off-by: Fabiano Rosas <faro...@linux.ibm.com>
> ---
Thanks for the quick fix :)
Tested-by: Greg Kurz <gr...@kaod.org>
> arch/powerpc/kvm/book3s_hv_uvmem.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c
> b/arch/powerpc/kvm/book3s_hv_uvmem.c
> index 79b1202b1c62..9d26614b2a77 100644
> --- a/arch/powerpc/kvm/book3s_hv_uvmem.c
> +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
> @@ -806,6 +806,9 @@ int kvmppc_uvmem_init(void)
>
> void kvmppc_uvmem_free(void)
> {
> + if (!kvmppc_uvmem_bitmap)
> + return;
> +
> memunmap_pages(&kvmppc_uvmem_pgmap);
> release_mem_region(kvmppc_uvmem_pgmap.res.start,
> resource_size(&kvmppc_uvmem_pgmap.res));
