| Message ID | CANRm+Cx2ifbbQWk0yAm=W5Us69GybSdtO8uLYXx-qe9F=jNeeQ@mail.gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3,1/2] KVM: X86: Less kvmclock sync induced vmexits after VM boots | expand |
On 17/02/20 11:37, Wanpeng Li wrote: > From: wanpeng li <wanpengli@tencent.com> > > For the duration of mapping eVMCS, it derefences ->memslots without holding > ->srcu or ->slots_lock when accessing hv assist page. This patch fixes it by > moving nested_sync_vmcs12_to_shadow to prepare_guest_switch, where the SRCU > is already taken. > > It can be reproduced by running kvm's evmcs_test selftest. > > ============================= > warning: suspicious rcu usage > 5.6.0-rc1+ #53 tainted: g w ioe > ----------------------------- > ./include/linux/kvm_host.h:623 suspicious rcu_dereference_check() usage! > > other info that might help us debug this: > > rcu_scheduler_active = 2, debug_locks = 1 > 1 lock held by evmcs_test/8507: > #0: ffff9ddd156d00d0 (&vcpu->mutex){+.+.}, at: > kvm_vcpu_ioctl+0x85/0x680 [kvm] > > stack backtrace: > cpu: 6 pid: 8507 comm: evmcs_test tainted: g w ioe 5.6.0-rc1+ #53 > hardware name: dell inc. optiplex 7040/0jctf8, bios 1.4.9 09/12/2016 > call trace: > dump_stack+0x68/0x9b > kvm_read_guest_cached+0x11d/0x150 [kvm] > kvm_hv_get_assist_page+0x33/0x40 [kvm] > nested_enlightened_vmentry+0x2c/0x60 [kvm_intel] > nested_vmx_handle_enlightened_vmptrld.part.52+0x32/0x1c0 [kvm_intel] > nested_sync_vmcs12_to_shadow+0x439/0x680 [kvm_intel] > vmx_vcpu_run+0x67a/0xe60 [kvm_intel] > vcpu_enter_guest+0x35e/0x1bc0 [kvm] > kvm_arch_vcpu_ioctl_run+0x40b/0x670 [kvm] > kvm_vcpu_ioctl+0x370/0x680 [kvm] > ksys_ioctl+0x235/0x850 > __x64_sys_ioctl+0x16/0x20 > do_syscall_64+0x77/0x780 > entry_syscall_64_after_hwframe+0x49/0xbe > > Signed-off-by: Wanpeng Li <wanpengli@tencent.com> > --- > v1 -> v2: > * update Subject > * move the check above > * add the WARN_ON_ONCE > > arch/x86/kvm/vmx/vmx.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 3be25ec..9a6797f 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -1175,6 +1175,10 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) > vmx->guest_msrs[i].mask); > > } > + > + if (vmx->nested.need_vmcs12_to_shadow_sync) > + nested_sync_vmcs12_to_shadow(vcpu); > + > if (vmx->guest_state_loaded) > return; > > @@ -6482,8 +6486,7 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) > vmcs_write32(PLE_WINDOW, vmx->ple_window); > } > > - if (vmx->nested.need_vmcs12_to_shadow_sync) > - nested_sync_vmcs12_to_shadow(vcpu); > + WARN_ON_ONCE(vmx->nested.need_vmcs12_to_shadow_sync); > > if (kvm_register_is_dirty(vcpu, VCPU_REGS_RSP)) > vmcs_writel(GUEST_RSP, vcpu->arch.regs[VCPU_REGS_RSP]); > -- > 2.7.4 > Queued, thanks. But the whitespace in the patch is messed up. Paolo
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 3be25ec..9a6797f 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1175,6 +1175,10 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu) vmx->guest_msrs[i].mask); } + + if (vmx->nested.need_vmcs12_to_shadow_sync) + nested_sync_vmcs12_to_shadow(vcpu); + if (vmx->guest_state_loaded) return; @@ -6482,8 +6486,7 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) vmcs_write32(PLE_WINDOW, vmx->ple_window); } - if (vmx->nested.need_vmcs12_to_shadow_sync) - nested_sync_vmcs12_to_shadow(vcpu); + WARN_ON_ONCE(vmx->nested.need_vmcs12_to_shadow_sync); if (kvm_register_is_dirty(vcpu, VCPU_REGS_RSP)) vmcs_writel(GUEST_RSP, vcpu->arch.regs[VCPU_REGS_RSP]);