Hi Christoffer, On Mon, Jul 31, 2017 at 8:59 AM, Christoffer Dall <cdall@xxxxxxxxxx> wrote: > On Tue, Jul 18, 2017 at 11:59:04AM -0500, Jintack Lim wrote: >> Forward CPACR_EL1 traps to the virtual EL2 if virtual CPTR_EL2 is >> configured to trap CPACR_EL1 accesses from EL1. >> >> This is for recursive nested virtualization. >> >> Signed-off-by: Jintack Lim <jintack.lim@xxxxxxxxxx> >> --- >> arch/arm64/kvm/sys_regs.c | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c >> index 6f67666..ba2966d 100644 >> --- a/arch/arm64/kvm/sys_regs.c >> +++ b/arch/arm64/kvm/sys_regs.c >> @@ -1091,6 +1091,11 @@ static bool access_cpacr(struct kvm_vcpu *vcpu, >> if (el12_reg(p) && forward_nv_traps(vcpu)) >> return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu)); >> >> + /* Forward this trap to the virtual EL2 if CPTR_EL2.TCPAC is set*/ >> + if (!el12_reg(p) && !vcpu_mode_el2(vcpu) && >> + (vcpu_sys_reg(vcpu, CPTR_EL2) & CPTR_EL2_TCPAC)) >> + return kvm_inject_nested_sync(vcpu, kvm_vcpu_get_hsr(vcpu)); >> + > > I'm trying to understand what should happen if the VM is in EL1 and > accesses CPACR_EL12, but the guest hypervisor did not set > CPTR_EL2.TCPAC, why would we get here, and if there's a good reason why I guess what you meant is HCR_EL2.NV bit? > we god here, is the EL12 access not supposed to undef at EL1 as opposed > to actually work, like it seems your code does when it doesn't take the > branch? IIUC, we need to have this logic if (el12_reg() && virtual HCR_EL2.NV == 0) inject_undef(); This is a good point, and should be applied for all traps controlled by NV bit. > >> /* >> * When the virtual HCR_EL2.E2H == 1, an access to CPACR_EL1 >> * in the virtual EL2 is to access CPTR_EL2. >> -- >> 1.9.1 >> > > Thanks, > -Christoffer
