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Message-ID: <b791a3f6-a5ab-4f7e-bb2a-d277b26ec2c4@redhat.com>
Date: Tue, 10 Sep 2024 12:04:36 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Rick Edgecombe <rick.p.edgecombe@...el.com>, seanjc@...gle.com,
kvm@...r.kernel.org
Cc: kai.huang@...el.com, dmatlack@...gle.com, isaku.yamahata@...il.com,
yan.y.zhao@...el.com, nik.borisov@...e.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 17/21] KVM: TDX: MTRR: implement get_mt_mask() for TDX
On 9/4/24 05:07, Rick Edgecombe wrote:
> From: Isaku Yamahata <isaku.yamahata@...el.com>
>
> Although TDX supports only WB for private GPA, it's desirable to support
> MTRR for shared GPA. Always honor guest PAT for shared EPT as what's done
> for normal VMs.
>
> Suggested-by: Kai Huang <kai.huang@...el.com>
> Co-developed-by: Yan Zhao <yan.y.zhao@...el.com>
> Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
> ---
> TDX MMU part 2 v1:
> - Align with latest vmx code in kvm/queue.
> - Updated patch log.
> - Dropped KVM_BUG_ON() in vt_get_mt_mask(). (Rick)
The only difference at this point is
if (!static_cpu_has(X86_FEATURE_SELFSNOOP) &&
!kvm_arch_has_noncoherent_dma(vcpu->kvm))
return (MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT) |
VMX_EPT_IPAT_BIT;
which should never be true. I think this patch can simply be dropped.
Paolo
> +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))
> @@ -292,7 +300,7 @@ 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 435112562954..50ce24905062 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -374,6 +374,14 @@ 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;
> +
> + 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 66829413797d..d8a00ab4651c 100644
> --- a/arch/x86/kvm/vmx/x86_ops.h
> +++ b/arch/x86/kvm/vmx/x86_ops.h
> @@ -128,6 +128,7 @@ 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);
>
> @@ -153,6 +154,7 @@ 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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