On Fri, Feb 22, 2019 at 12:18:18PM +0000, Andre Przywara wrote: > Add documentation for the newly defined firmware registers to save and > restore any vulnerability migitation status. > > Signed-off-by: Andre Przywara <andre.przywara at arm.com> > --- > Documentation/virtual/kvm/arm/psci.txt | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/Documentation/virtual/kvm/arm/psci.txt b/Documentation/virtual/kvm/arm/psci.txt > index aafdab887b04..fe8930765cc7 100644 > --- a/Documentation/virtual/kvm/arm/psci.txt > +++ b/Documentation/virtual/kvm/arm/psci.txt > @@ -28,3 +28,27 @@ The following register is defined: > - Allows any PSCI version implemented by KVM and compatible with > v0.2 to be set with SET_ONE_REG > - Affects the whole VM (even if the register view is per-vcpu) Doh, ignore my comments about undescribed semantics in the last patch. > + > +* KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1: > + Holds the state of the firmware controlled workaround to mitigate > + CVE-2017-5715, as described under SMCCC_ARCH_WORKAROUND_1 in [1]. > + Accepted values are: > + KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL: Workaround not available. > + The mitigation status for the guest is unknown. > + KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_AVAIL: Workaround active for the guest. > + KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_UNAFFECTED: The workaround is not > + available and not needed. > + > +* KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2: > + Holds the state of the firmware controlled workaround to mitigate > + CVE-2018-3639, as described under SMCCC_ARCH_WORKAROUND_2 in [1]. > + Accepted values are: > + KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL: Workaround not available. > + KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN: Workaround state unknown. > + KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL: Workaround available, and can > + be disabled by a vCPU. If KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED is > + set, it is active for this vCPU. Ah, so this is really not supposed to be set except for _AVAIL? > + KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNAFFECTED: Workaround always active > + or not needed. But is the workaround available (i.e., SMCCC interface implemented?) The code assumes it is, IIUC -- i.e., it will happily upgrade _AVAIL to _UNAFFECTED. That's bad if it means the SMCCC call disappears under the guest's feet. (Not saying it does, just that I'm not sure.) For KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1, we apply an == check, avoiding this subtlety. Cheers ---Dave
