Re: [PATCH] KVM: VMX: fix tlb flush with invalid root

Marcelo Tosatti
2010-07-05T01:02:11Z

On Sat, Jul 03, 2010 at 04:02:42PM +0800, Xiao Guangrong wrote:
> Commit 341d9b535b6c simplify reload logic while entry guest mode, it
> can avoid unnecessary sync-root if KVM_REQ_MMU_RELOAD and
> KVM_REQ_MMU_SYNC both set.
>
> But, it cause a issue that when we handle 'KVM_REQ_TLB_FLUSH', the
> root is invalid, it is triggered during my test:
>
> Kernel BUG at ffffffffa00212b8 [verbose debug info unavailable]
> ......
>
> [<ffffffff810f5caf>] ? fget_light+0x111/0x28e
> [<ffffffff81103963>] sys_ioctl+0x47/0x6a
> [<ffffffff81002c1b>] system_call_fastpath+0x16/0x1b
> Code: f0 eb 21 f7 c2 00 00 00 04 74 22 48 8d 45 f0 48 c7 45 f0 00 00 00 00 48 c7 45 f8 00 00 00 00 b9 02 00 00 00 66 0f 38 80 08 77 02 <0f> 0b c9 c3 55 48 89 e5 0f 1f 44 00 00 ba 00 68 00 00 48 8b 8f
> RIP [<ffffffffa00212b8>] vmx_flush_tlb+0xdf/0xe3 [kvm_intel]
> RSP <ffff8800be269ca8>
>
> Fixed by directly return if the root is not ready.
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>

Applied, thanks.