| Message ID | 51422773.9010901@siemens.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2013-03-14 20:39, Jan Kiszka wrote: > vmx_vcpu_reset may now be called while already holding the srcu lock, so > we may overwrite what was already saved there. Save and restore it. > > Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> > --- > > Even if this should be unneeded, it looks more consistent. In any case, > all versions on the table, pick what you prefer. > > arch/x86/kvm/vmx.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 958ac3a..7bc49ca 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -4117,6 +4117,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu) > { > struct vcpu_vmx *vmx = to_vmx(vcpu); > u64 msr; > + int idx; > > vmx->rmode.vm86_active = 0; > > @@ -4190,9 +4191,11 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu) > vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->vpid); > > vmx->vcpu.arch.cr0 = X86_CR0_NW | X86_CR0_CD | X86_CR0_ET; > + idx = vcpu->srcu_idx; > vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); > vmx_set_cr0(&vmx->vcpu, kvm_read_cr0(vcpu)); /* enter rmode */ > srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); > + vcpu->srcu_idx = idx; > vmx_set_cr4(&vmx->vcpu, 0); > vmx_set_efer(&vmx->vcpu, 0); > vmx_fpu_activate(&vmx->vcpu); > This cannot work either: I think we really need to drop the srcu lock before calling vmx_set_tss_addr. But if we nest the lock, we may only drop it once now in enter_rmode. OK, I'll propose a patch to remove that TSS bug workaround from enter_rmode. Will dig a bit in the archives as well to check which version of qemu-kvm was actually exposing this. Jan
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 958ac3a..7bc49ca 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -4117,6 +4117,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu) { struct vcpu_vmx *vmx = to_vmx(vcpu); u64 msr; + int idx; vmx->rmode.vm86_active = 0; @@ -4190,9 +4191,11 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu) vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->vpid); vmx->vcpu.arch.cr0 = X86_CR0_NW | X86_CR0_CD | X86_CR0_ET; + idx = vcpu->srcu_idx; vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu); vmx_set_cr0(&vmx->vcpu, kvm_read_cr0(vcpu)); /* enter rmode */ srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx); + vcpu->srcu_idx = idx; vmx_set_cr4(&vmx->vcpu, 0); vmx_set_efer(&vmx->vcpu, 0); vmx_fpu_activate(&vmx->vcpu);
vmx_vcpu_reset may now be called while already holding the srcu lock, so we may overwrite what was already saved there. Save and restore it. Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com> --- Even if this should be unneeded, it looks more consistent. In any case, all versions on the table, pick what you prefer. arch/x86/kvm/vmx.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-)