On Tue, Apr 09, 2024 at 12:05:12PM -0700, Sean Christopherson wrote: > On Tue, Mar 19, 2024, Tao Su wrote: > > Intel MKTME repurposes several high bits of physical address as 'keyID', > > so boot_cpu_data.x86_phys_bits doesn't hold physical address bits reported > > by CPUID anymore. > > > > If guest.MAXPHYADDR < host.MAXPHYADDR, the bit field of ‘keyID’ belongs > > to reserved bits in guest’s view, so intercepting #PF to fix error code > > is necessary, just replace boot_cpu_data.x86_phys_bits with > > kvm_get_shadow_phys_bits() to fix. > > > > Signed-off-by: Tao Su <tao1.su@xxxxxxxxxxxxxxx> > > --- > > arch/x86/kvm/vmx/vmx.h | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h > > index 65786dbe7d60..79b1757df74a 100644 > > --- a/arch/x86/kvm/vmx/vmx.h > > +++ b/arch/x86/kvm/vmx/vmx.h > > @@ -15,6 +15,7 @@ > > #include "vmx_ops.h" > > #include "../cpuid.h" > > #include "run_flags.h" > > +#include "../mmu.h" > > > > #define MSR_TYPE_R 1 > > #define MSR_TYPE_W 2 > > @@ -719,7 +720,8 @@ static inline bool vmx_need_pf_intercept(struct kvm_vcpu *vcpu) > > if (!enable_ept) > > return true; > > > > - return allow_smaller_maxphyaddr && cpuid_maxphyaddr(vcpu) < boot_cpu_data.x86_phys_bits; > > + return allow_smaller_maxphyaddr && > > + cpuid_maxphyaddr(vcpu) < kvm_get_shadow_phys_bits(); > > For posterity, because I had a brief moment where I thought we done messed up: > > No change is needed in the reporting of MAXPHYADDR in KVM_GET_SUPPORTED_CPUID, > as reporting boot_cpu_data.x86_phys_bits as MAXPHYADDR when TDP is disabled is ok > because KVM always intercepts #PF when TDP is disabled, and KVM already reports > the full/raw MAXPHYADDR when TDP is enabled. You are right, but userspace can fully control guest.MAXPHYADDR when TDP is enabled. Please see the unit-test[*], I think this issue could show up earlier if phys-bits is set larger, such as 46-bits. [*] https://gitlab.com/kvm-unit-tests/kvm-unit-tests/-/blob/master/x86/unittests.cfg?ref_type=heads#L156
