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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Apr 30, 2020 at 01:45:51PM +0100, Marc Zyngier wrote: > On 2020-04-30 13:31, Will Deacon wrote: > > On Thu, Apr 30, 2020 at 11:59:05AM +0100, Marc Zyngier wrote: > > > On 2020-04-30 11:25, Will Deacon wrote: > > > > On Thu, Apr 30, 2020 at 11:15:13AM +0100, Marc Zyngier wrote: > > > > > diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c > > > > > index 23ebe51410f0..2a159af82429 100644 > > > > > --- a/arch/arm64/kvm/guest.c > > > > > +++ b/arch/arm64/kvm/guest.c > > > > > @@ -200,6 +200,10 @@ static int set_core_reg(struct kvm_vcpu *vcpu, > > > > > const struct kvm_one_reg *reg) > > > > > } > > > > > > > > > > memcpy((u32 *)regs + off, valp, KVM_REG_SIZE(reg->id)); > > > > > + > > > > > + if (*vcpu_cpsr(vcpu) & PSR_AA32_MODE_MASK) > > > > > + *vcpu_pc(vcpu) = lower_32_bits(*vcpu_pc(vcpu)); > > > > > > > > It seems slightly odd to me that we don't enforce this for *all* the > > > > registers when running as a 32-bit guest. Couldn't userspace be equally > > > > confused by a 64-bit lr or sp? > > > > > > Fair point. How about this on top, which wipes the upper 32 bits for > > > each and every register in the current mode: > > > > > > diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c > > > index 2a159af82429..f958c3c7bf65 100644 > > > --- a/arch/arm64/kvm/guest.c > > > +++ b/arch/arm64/kvm/guest.c > > > @@ -201,9 +201,12 @@ static int set_core_reg(struct kvm_vcpu *vcpu, > > > const > > > struct kvm_one_reg *reg) > > > > > > memcpy((u32 *)regs + off, valp, KVM_REG_SIZE(reg->id)); > > > > > > - if (*vcpu_cpsr(vcpu) & PSR_AA32_MODE_MASK) > > > - *vcpu_pc(vcpu) = lower_32_bits(*vcpu_pc(vcpu)); > > > + if (*vcpu_cpsr(vcpu) & PSR_AA32_MODE_MASK) { > > > + int i; > > > > > > + for (i = 0; i < 16; i++) > > > + *vcpu_reg32(vcpu, i) = (u32)*vcpu_reg32(vcpu, i); > > > > I think you're missing all the funny banked registers that live all the > > way > > up to x30 iirc. > > No, they are all indirected via vcpu_reg32(), which has the magic tables. > And the whole point is that we only want to affect the current mode (no > point > in repainting the FIQ registers if the PSR says USR). > > Or am I missing something obvious? Nope, just my inability to parse vcpu_reg32 the first time around! So, for the updated patch: Acked-by: Will Deacon