On Tue, Oct 05, 2021 at 08:05:02AM -0700, Oliver Upton wrote:
> Hi folks,
>
> On Tue, Oct 5, 2021 at 6:33 AM Andrew Jones <drjones@xxxxxxxxxx> wrote:
> >
> > On Fri, Oct 01, 2021 at 09:10:14AM -0700, Oliver Upton wrote:
> > > On Thu, Sep 30, 2021 at 11:05 PM Reiji Watanabe <reijiw@xxxxxxxxxx> wrote:
> > > >
> > > > On Thu, Sep 23, 2021 at 12:16 PM Oliver Upton <oupton@xxxxxxxxxx> wrote:
> > > > >
> > > > > In its implementation of the PSCI function, KVM needs to request that a
> > > > > target vCPU resets before its next entry into the guest. Wrap the logic
> > > > > for requesting a reset in a function for later use by other implemented
> > > > > PSCI calls.
> > > > >
> > > > > No functional change intended.
> > > > >
> > > > > Signed-off-by: Oliver Upton <oupton@xxxxxxxxxx>
> > > > > ---
> > > > > arch/arm64/kvm/psci.c | 59 +++++++++++++++++++++++++------------------
> > > > > 1 file changed, 35 insertions(+), 24 deletions(-)
> > > > >
> > > > > diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
> > > > > index 310b9cb2b32b..bb59b692998b 100644
> > > > > --- a/arch/arm64/kvm/psci.c
> > > > > +++ b/arch/arm64/kvm/psci.c
> > > > > @@ -64,9 +64,40 @@ static inline bool kvm_psci_valid_affinity(unsigned long affinity)
> > > > > return !(affinity & ~MPIDR_HWID_BITMASK);
> > > > > }
> > > > >
> > > > > -static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
> > > > > +static void kvm_psci_vcpu_request_reset(struct kvm_vcpu *vcpu,
> > > > > + unsigned long entry_addr,
> > > > > + unsigned long context_id,
> > > > > + bool big_endian)
> > > > > {
> > > > > struct vcpu_reset_state *reset_state;
> > > > > +
> > > > > + lockdep_assert_held(&vcpu->kvm->lock);
> > > > > +
> > > > > + reset_state = &vcpu->arch.reset_state;
> > > > > + reset_state->pc = entry_addr;
> > > > > +
> > > > > + /* Propagate caller endianness */
> > > > > + reset_state->be = big_endian;
> > > > > +
> > > > > + /*
> > > > > + * NOTE: We always update r0 (or x0) because for PSCI v0.1
> > > > > + * the general purpose registers are undefined upon CPU_ON.
> > > > > + */
> > > > > + reset_state->r0 = context_id;
> > > > > +
> > > > > + WRITE_ONCE(reset_state->reset, true);
> > > > > + kvm_make_request(KVM_REQ_VCPU_RESET, vcpu);
> > > > > +
> > > > > + /*
> > > > > + * Make sure the reset request is observed if the change to
> > > > > + * power_state is observed.
> > > > > + */
> > > > > + smp_wmb();
> > > > > + vcpu->arch.power_off = false;
> > > > > +}
> > > > > +
> > > > > +static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
> > > > > +{
> > > > > struct kvm *kvm = source_vcpu->kvm;
> > > > > struct kvm_vcpu *vcpu = NULL;
> > > > > unsigned long cpu_id;
> > > > > @@ -90,29 +121,9 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
> > > > > return PSCI_RET_INVALID_PARAMS;
> > > > > }
> > > > >
> > > > > - reset_state = &vcpu->arch.reset_state;
> > > > > -
> > > > > - reset_state->pc = smccc_get_arg2(source_vcpu);
> > > > > -
> > > > > - /* Propagate caller endianness */
> > > > > - reset_state->be = kvm_vcpu_is_be(source_vcpu);
> > > > > -
> > > > > - /*
> > > > > - * NOTE: We always update r0 (or x0) because for PSCI v0.1
> > > > > - * the general purpose registers are undefined upon CPU_ON.
> > > > > - */
> > > > > - reset_state->r0 = smccc_get_arg3(source_vcpu);
> > > > > -
> > > > > - WRITE_ONCE(reset_state->reset, true);
> > > > > - kvm_make_request(KVM_REQ_VCPU_RESET, vcpu);
> > > > > -
> > > > > - /*
> > > > > - * Make sure the reset request is observed if the change to
> > > > > - * power_state is observed.
> > > > > - */
> > > > > - smp_wmb();
> > > > > -
> > > > > - vcpu->arch.power_off = false;
> > > > > + kvm_psci_vcpu_request_reset(vcpu, smccc_get_arg2(source_vcpu),
> > > > > + smccc_get_arg3(source_vcpu),
> > > > > + kvm_vcpu_is_be(source_vcpu));
> > > > > kvm_vcpu_wake_up(vcpu);
> > > > >
> > > > > return PSCI_RET_SUCCESS;
> > > > > --
> > > > > 2.33.0.685.g46640cef36-goog
> > > >
> > > > Reviewed-by: Reiji Watanabe <reijiw@xxxxxxxxxx>
> > > >
> > > > Not directly related to the patch, but the (original) code doesn't
> > > > do any sanity checking for the entry address although the PSCI spec says:
> > > >
> > > > "INVALID_ADDRESS is returned when the entry point address is known
> > > > by the implementation to be invalid, because it is in a range that
> > > > is known not to be available to the caller."
> > >
> > > Right, I had noticed the same but was a tad too lazy to address in
> > > this series :) Thanks for the review, Reji!
> > >
> >
> > KVM doesn't reserve any subrange within [0 - max_ipa), afaik. So all
> > we need to do is check 'entry_addr < max_ipa', right?
> >
>
> We could be a bit more pedantic and check if the IPA exists in a
> memory slot, seems like kvm_vcpu_is_visible_gfn() should do the trick.
>
> Thoughts?
Are we sure that all emulated devices, nvram, etc. will always use a
memslot for regions that contain executable code? If there's any doubt,
then we can't be sure about non-memslot regions within the max_ipa range.
That'd be up to userspace.
Thanks,
drew
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