Messages in this thread | | | Date | Mon, 19 Feb 2024 13:20:58 +0800 | Subject | Re: [PATCH v18 061/121] KVM: TDX: MTRR: implement get_mt_mask() for TDX | From | Binbin Wu <> |
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On 1/23/2024 7:53 AM, isaku.yamahata@intel.com wrote: > From: Isaku Yamahata <isaku.yamahata@intel.com> > > Because TDX virtualize cpuid[0x1].EDX[MTRR: bit 12] to fixed 1, guest TD > thinks MTRR is supported. Although TDX supports only WB for private GPA, > it's desirable to support MTRR for shared GPA. As guest access to MTRR > MSRs causes #VE and KVM/x86 tracks the values of MTRR MSRs, the remining
s/remining/remaining
> part is to implement get_mt_mask method for TDX for shared GPA. > > Pass around shared bit from kvm fault handler to get_mt_mask method so that > it can determine if the gfn is shared or private. Implement get_mt_mask() > following vmx case for shared GPA and return WB for private GPA.
But the shared bit is not consumed in get_mt_mask()?
> the existing vmx_get_mt_mask() can't be directly used as CPU state(CR0.CD) > is protected. GFN passed to kvm_mtrr_check_gfn_range_consistency() should > include shared bit. > > Suggested-by: Kai Huang <kai.huang@intel.com> > Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com> > --- > arch/x86/kvm/vmx/main.c | 10 +++++++++- > arch/x86/kvm/vmx/tdx.c | 23 +++++++++++++++++++++++ > arch/x86/kvm/vmx/x86_ops.h | 2 ++ > 3 files changed, 34 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c > index 569f2f67094c..0784290d846f 100644 > --- a/arch/x86/kvm/vmx/main.c > +++ b/arch/x86/kvm/vmx/main.c > @@ -232,6 +232,14 @@ static void vt_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, > vmx_load_mmu_pgd(vcpu, root_hpa, pgd_level); > } > > +static u8 vt_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) > +{ > + if (is_td_vcpu(vcpu)) > + return tdx_get_mt_mask(vcpu, gfn, is_mmio); > + > + return vmx_get_mt_mask(vcpu, gfn, is_mmio); > +} > + > static int vt_mem_enc_ioctl(struct kvm *kvm, void __user *argp) > { > if (!is_td(kvm)) > @@ -351,7 +359,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = { > > .set_tss_addr = vmx_set_tss_addr, > .set_identity_map_addr = vmx_set_identity_map_addr, > - .get_mt_mask = vmx_get_mt_mask, > + .get_mt_mask = vt_get_mt_mask, > > .get_exit_info = vmx_get_exit_info, > > diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c > index 4002e7e7b191..4cbcedff4f16 100644 > --- a/arch/x86/kvm/vmx/tdx.c > +++ b/arch/x86/kvm/vmx/tdx.c > @@ -439,6 +439,29 @@ int tdx_vm_init(struct kvm *kvm) > return 0; > } > > +u8 tdx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) > +{ > + if (is_mmio) > + return MTRR_TYPE_UNCACHABLE << VMX_EPT_MT_EPTE_SHIFT; > + > + if (!kvm_arch_has_noncoherent_dma(vcpu->kvm)) > + return (MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT) | VMX_EPT_IPAT_BIT; > + > + /* > + * TDX enforces CR0.CD = 0 and KVM MTRR emulation enforces writeback. > + * TODO: implement MTRR MSR emulation so that > + * MTRRCap: SMRR=0: SMRR interface unsupported > + * WC=0: write combining unsupported > + * FIX=0: Fixed range registers unsupported > + * VCNT=0: number of variable range regitsers = 0 > + * MTRRDefType: E=1, FE=0, type=writeback only. Don't allow other value. > + * E=1: enable MTRR > + * FE=0: disable fixed range MTRRs > + * type: default memory type=writeback > + */ > + return MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT; > +} > + > int tdx_vcpu_create(struct kvm_vcpu *vcpu) > { > struct kvm_tdx *kvm_tdx = to_kvm_tdx(vcpu->kvm); > diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h > index 441915e9293e..5a9aabf39c02 100644 > --- a/arch/x86/kvm/vmx/x86_ops.h > +++ b/arch/x86/kvm/vmx/x86_ops.h > @@ -150,6 +150,7 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp); > int tdx_vcpu_create(struct kvm_vcpu *vcpu); > void tdx_vcpu_free(struct kvm_vcpu *vcpu); > void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event); > +u8 tdx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio); > > int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp); > > @@ -176,6 +177,7 @@ static inline int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) { return -EOP > static inline int tdx_vcpu_create(struct kvm_vcpu *vcpu) { return -EOPNOTSUPP; } > static inline void tdx_vcpu_free(struct kvm_vcpu *vcpu) {} > static inline void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) {} > +static inline u8 tdx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio) { return 0; } > > static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) { return -EOPNOTSUPP; } >
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