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SubjectRe: [RFC PATCH v5 043/104] KVM: TDX: Add load_mmu_pgd method for TDX
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On 3/4/22 20:48, isaku.yamahata@intel.com wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
>
> For virtual IO, the guest TD shares guest pages with VMM without
> encryption. Shared EPT is used to map guest pages in unprotected way.
>
> Add the VMCS field encoding for the shared EPTP, which will be used by
> TDX to have separate EPT walks for private GPAs (existing EPTP) versus
> shared GPAs (new shared EPTP).
>
> Set shared EPT pointer value for the TDX guest to initialize TDX MMU.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
> arch/x86/include/asm/vmx.h | 1 +
> arch/x86/kvm/vmx/main.c | 11 ++++++++++-
> arch/x86/kvm/vmx/tdx.c | 5 +++++
> arch/x86/kvm/vmx/x86_ops.h | 4 ++++
> 4 files changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> index 88d9b8cc7dde..a2402d1bde04 100644
> --- a/arch/x86/include/asm/vmx.h
> +++ b/arch/x86/include/asm/vmx.h
> @@ -221,6 +221,7 @@ enum vmcs_field {
> ENCLS_EXITING_BITMAP_HIGH = 0x0000202F,
> TSC_MULTIPLIER = 0x00002032,
> TSC_MULTIPLIER_HIGH = 0x00002033,
> + SHARED_EPT_POINTER = 0x0000203C,
> GUEST_PHYSICAL_ADDRESS = 0x00002400,
> GUEST_PHYSICAL_ADDRESS_HIGH = 0x00002401,
> VMCS_LINK_POINTER = 0x00002800,
> diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> index b242a9dc9e29..6969e3557bd4 100644
> --- a/arch/x86/kvm/vmx/main.c
> +++ b/arch/x86/kvm/vmx/main.c
> @@ -89,6 +89,15 @@ static void vt_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> return vmx_vcpu_reset(vcpu, init_event);
> }
>
> +static void vt_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa,
> + int pgd_level)
> +{
> + if (is_td_vcpu(vcpu))
> + return tdx_load_mmu_pgd(vcpu, root_hpa, pgd_level);
> +
> + vmx_load_mmu_pgd(vcpu, root_hpa, pgd_level);
> +}
> +
> static int vt_mem_enc_op(struct kvm *kvm, void __user *argp)
> {
> if (!is_td(kvm))
> @@ -205,7 +214,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
> .write_tsc_offset = vmx_write_tsc_offset,
> .write_tsc_multiplier = vmx_write_tsc_multiplier,
>
> - .load_mmu_pgd = vmx_load_mmu_pgd,
> + .load_mmu_pgd = vt_load_mmu_pgd,
>
> .check_intercept = vmx_check_intercept,
> .handle_exit_irqoff = vmx_handle_exit_irqoff,
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index c3434b33c452..51098e10b6a0 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -496,6 +496,11 @@ void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> vcpu->kvm->vm_bugged = true;
> }
>
> +void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int pgd_level)
> +{
> + td_vmcs_write64(to_tdx(vcpu), SHARED_EPT_POINTER, root_hpa & PAGE_MASK);
> +}
> +
> static int tdx_capabilities(struct kvm *kvm, struct kvm_tdx_cmd *cmd)
> {
> struct kvm_tdx_capabilities __user *user_caps;
> diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
> index 81f246493ec7..ad9b1c883761 100644
> --- a/arch/x86/kvm/vmx/x86_ops.h
> +++ b/arch/x86/kvm/vmx/x86_ops.h
> @@ -143,6 +143,8 @@ void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event);
>
> int tdx_vm_ioctl(struct kvm *kvm, void __user *argp);
> int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp);
> +
> +void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level);
> #else
> static inline void tdx_pre_kvm_init(
> unsigned int *vcpu_size, unsigned int *vcpu_align, unsigned int *vm_size) {}
> @@ -160,6 +162,8 @@ static inline void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) {}
>
> static inline int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) { return -EOPNOTSUPP; }
> static inline int tdx_vcpu_ioctl(struct kvm_vcpu *vcpu, void __user *argp) { return -EOPNOTSUPP; }
> +
> +static inline void tdx_load_mmu_pgd(struct kvm_vcpu *vcpu, hpa_t root_hpa, int root_level) {}
> #endif
>
> #endif /* __KVM_X86_VMX_X86_OPS_H */

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>

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