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Message-ID: <9d024bfc-4b1d-4da5-81ba-36e60cf5e284@linux.intel.com>
Date: Mon, 5 Feb 2024 10:23:34 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: isaku.yamahata@...el.com
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
isaku.yamahata@...il.com, Paolo Bonzini <pbonzini@...hat.com>,
erdemaktas@...gle.com, Sean Christopherson <seanjc@...gle.com>,
Sagi Shahar <sagis@...gle.com>, Kai Huang <kai.huang@...el.com>,
chen.bo@...el.com, hang.yuan@...el.com, tina.zhang@...el.com,
Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [PATCH v18 057/121] KVM: TDX: Add load_mmu_pgd method for TDX
On 1/23/2024 7:53 AM, isaku.yamahata@...el.com wrote:
> From: Sean Christopherson <sean.j.christopherson@...el.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@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
> arch/x86/include/asm/vmx.h | 1 +
> arch/x86/kvm/vmx/main.c | 13 ++++++++++++-
> arch/x86/kvm/vmx/tdx.c | 5 +++++
> arch/x86/kvm/vmx/x86_ops.h | 4 ++++
> 4 files changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> index f703bae0c4ac..9deb663a42e3 100644
> --- a/arch/x86/include/asm/vmx.h
> +++ b/arch/x86/include/asm/vmx.h
> @@ -236,6 +236,7 @@ enum vmcs_field {
> TSC_MULTIPLIER_HIGH = 0x00002033,
> TERTIARY_VM_EXEC_CONTROL = 0x00002034,
> TERTIARY_VM_EXEC_CONTROL_HIGH = 0x00002035,
> + SHARED_EPT_POINTER = 0x0000203C,
> PID_POINTER_TABLE = 0x00002042,
> PID_POINTER_TABLE_HIGH = 0x00002043,
> GUEST_PHYSICAL_ADDRESS = 0x00002400,
> diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> index 8059b44ed159..f55ac09edc60 100644
> --- a/arch/x86/kvm/vmx/main.c
> +++ b/arch/x86/kvm/vmx/main.c
> @@ -147,6 +147,17 @@ static void vt_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> 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)) {
> + tdx_load_mmu_pgd(vcpu, root_hpa, pgd_level);
> + return;
> + }
> +
> + vmx_load_mmu_pgd(vcpu, root_hpa, pgd_level);
> +}
> +
> static int vt_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
> {
> if (!is_td(kvm))
> @@ -279,7 +290,7 @@ 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 59d170709f82..25510b6740a3 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -501,6 +501,11 @@ void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> */
> }
>
> +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);
If we have concern about the alignment of root_hpa, shouldn't we do some
check instead of masking the address quietly?
> +}
> +
> static int tdx_get_capabilities(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 5f8ee1c93cd1..a9e5caf880dd 100644
> --- a/arch/x86/kvm/vmx/x86_ops.h
> +++ b/arch/x86/kvm/vmx/x86_ops.h
> @@ -152,6 +152,8 @@ void tdx_vcpu_free(struct kvm_vcpu *vcpu);
> void tdx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event);
>
> 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 int tdx_hardware_setup(struct kvm_x86_ops *x86_ops) { return -EOPNOTSUPP; }
> static inline void tdx_hardware_unsetup(void) {}
> @@ -173,6 +175,8 @@ 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 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 */
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