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Date: Tue, 6 Jul 2021 16:46:41 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: isaku.yamahata@...el.com, Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
"H . Peter Anvin" <hpa@...or.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>, erdemaktas@...gle.com,
Connor Kuehl <ckuehl@...hat.com>,
Sean Christopherson <seanjc@...gle.com>, x86@...nel.org,
linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: isaku.yamahata@...il.com,
Sean Christopherson <sean.j.christopherson@...el.com>
Subject: Re: [RFC PATCH v2 61/69] KVM: VMX: Move AR_BYTES encoder/decoder
helpers to common.h
On 03/07/21 00:05, isaku.yamahata@...el.com wrote:
> From: Sean Christopherson <sean.j.christopherson@...el.com>
>
> Move the AR_BYTES helpers to common.h so that future patches can reuse
> them to decode/encode AR for TDX.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> ---
> arch/x86/kvm/vmx/common.h | 41 ++++++++++++++++++++++++++++++++++
> arch/x86/kvm/vmx/vmx.c | 47 ++++-----------------------------------
> 2 files changed, 45 insertions(+), 43 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/common.h b/arch/x86/kvm/vmx/common.h
> index aa6a569b87d1..755aaec85199 100644
> --- a/arch/x86/kvm/vmx/common.h
> +++ b/arch/x86/kvm/vmx/common.h
> @@ -4,6 +4,7 @@
>
> #include <linux/kvm_host.h>
>
> +#include <asm/kvm.h>
> #include <asm/traps.h>
> #include <asm/vmx.h>
>
> @@ -119,4 +120,44 @@ static inline int __vmx_handle_ept_violation(struct kvm_vcpu *vcpu, gpa_t gpa,
> return kvm_mmu_page_fault(vcpu, gpa, error_code, NULL, 0);
> }
>
> +static inline u32 vmx_encode_ar_bytes(struct kvm_segment *var)
> +{
> + u32 ar;
> +
> + if (var->unusable || !var->present)
> + ar = 1 << 16;
> + else {
> + ar = var->type & 15;
> + ar |= (var->s & 1) << 4;
> + ar |= (var->dpl & 3) << 5;
> + ar |= (var->present & 1) << 7;
> + ar |= (var->avl & 1) << 12;
> + ar |= (var->l & 1) << 13;
> + ar |= (var->db & 1) << 14;
> + ar |= (var->g & 1) << 15;
> + }
> +
> + return ar;
> +}
> +
> +static inline void vmx_decode_ar_bytes(u32 ar, struct kvm_segment *var)
> +{
> + var->unusable = (ar >> 16) & 1;
> + var->type = ar & 15;
> + var->s = (ar >> 4) & 1;
> + var->dpl = (ar >> 5) & 3;
> + /*
> + * Some userspaces do not preserve unusable property. Since usable
> + * segment has to be present according to VMX spec we can use present
> + * property to amend userspace bug by making unusable segment always
> + * nonpresent. vmx_encode_ar_bytes() already marks nonpresent
> + * segment as unusable.
> + */
> + var->present = !var->unusable;
> + var->avl = (ar >> 12) & 1;
> + var->l = (ar >> 13) & 1;
> + var->db = (ar >> 14) & 1;
> + var->g = (ar >> 15) & 1;
> +}
> +
> #endif /* __KVM_X86_VMX_COMMON_H */
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 3c3bfc80d2bb..40843ca2fb33 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -365,8 +365,6 @@ static const struct kernel_param_ops vmentry_l1d_flush_ops = {
> };
> module_param_cb(vmentry_l1d_flush, &vmentry_l1d_flush_ops, NULL, 0644);
>
> -static u32 vmx_segment_access_rights(struct kvm_segment *var);
> -
> void vmx_vmexit(void);
>
> #define vmx_insn_failed(fmt...) \
> @@ -2826,7 +2824,7 @@ static void fix_rmode_seg(int seg, struct kvm_segment *save)
> vmcs_write16(sf->selector, var.selector);
> vmcs_writel(sf->base, var.base);
> vmcs_write32(sf->limit, var.limit);
> - vmcs_write32(sf->ar_bytes, vmx_segment_access_rights(&var));
> + vmcs_write32(sf->ar_bytes, vmx_encode_ar_bytes(&var));
> }
>
> static void enter_rmode(struct kvm_vcpu *vcpu)
> @@ -3217,7 +3215,6 @@ void vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
> void vmx_get_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
> {
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> - u32 ar;
>
> if (vmx->rmode.vm86_active && seg != VCPU_SREG_LDTR) {
> *var = vmx->rmode.segs[seg];
> @@ -3231,23 +3228,7 @@ void vmx_get_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
> var->base = vmx_read_guest_seg_base(vmx, seg);
> var->limit = vmx_read_guest_seg_limit(vmx, seg);
> var->selector = vmx_read_guest_seg_selector(vmx, seg);
> - ar = vmx_read_guest_seg_ar(vmx, seg);
> - var->unusable = (ar >> 16) & 1;
> - var->type = ar & 15;
> - var->s = (ar >> 4) & 1;
> - var->dpl = (ar >> 5) & 3;
> - /*
> - * Some userspaces do not preserve unusable property. Since usable
> - * segment has to be present according to VMX spec we can use present
> - * property to amend userspace bug by making unusable segment always
> - * nonpresent. vmx_segment_access_rights() already marks nonpresent
> - * segment as unusable.
> - */
> - var->present = !var->unusable;
> - var->avl = (ar >> 12) & 1;
> - var->l = (ar >> 13) & 1;
> - var->db = (ar >> 14) & 1;
> - var->g = (ar >> 15) & 1;
> + vmx_decode_ar_bytes(vmx_read_guest_seg_ar(vmx, seg), var);
> }
>
> static u64 vmx_get_segment_base(struct kvm_vcpu *vcpu, int seg)
> @@ -3273,26 +3254,6 @@ int vmx_get_cpl(struct kvm_vcpu *vcpu)
> }
> }
>
> -static u32 vmx_segment_access_rights(struct kvm_segment *var)
> -{
> - u32 ar;
> -
> - if (var->unusable || !var->present)
> - ar = 1 << 16;
> - else {
> - ar = var->type & 15;
> - ar |= (var->s & 1) << 4;
> - ar |= (var->dpl & 3) << 5;
> - ar |= (var->present & 1) << 7;
> - ar |= (var->avl & 1) << 12;
> - ar |= (var->l & 1) << 13;
> - ar |= (var->db & 1) << 14;
> - ar |= (var->g & 1) << 15;
> - }
> -
> - return ar;
> -}
> -
> void vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
> {
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> @@ -3327,7 +3288,7 @@ void vmx_set_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg)
> if (is_unrestricted_guest(vcpu) && (seg != VCPU_SREG_LDTR))
> var->type |= 0x1; /* Accessed */
>
> - vmcs_write32(sf->ar_bytes, vmx_segment_access_rights(var));
> + vmcs_write32(sf->ar_bytes, vmx_encode_ar_bytes(var));
>
> out:
> vmx->emulation_required = emulation_required(vcpu);
> @@ -3374,7 +3335,7 @@ static bool rmode_segment_valid(struct kvm_vcpu *vcpu, int seg)
> var.dpl = 0x3;
> if (seg == VCPU_SREG_CS)
> var.type = 0x3;
> - ar = vmx_segment_access_rights(&var);
> + ar = vmx_encode_ar_bytes(&var);
>
> if (var.base != (var.selector << 4))
> return false;
>
Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>
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