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From: Paolo Bonzini <pbonzini@redhat.com>
To: Maxim Levitsky <mlevitsk@redhat.com>, kvm@vger.kernel.org
Cc: open list <linux-kernel@vger.kernel.org>,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	Wanpeng Li <wanpengli@tencent.com>,
	Ingo Molnar <mingo@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Sean Christopherson <seanjc@google.com>,
	Borislav Petkov <bp@alien8.de>, Joerg Roedel <joro@8bytes.org>,
	"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>, Jim Mattson <jmattson@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v3 7/8] KVM: x86: Introduce KVM_GET_SREGS2 / KVM_SET_SREGS2
Date: Thu, 10 Jun 2021 17:06:04 +0200	[thread overview]
Message-ID: <f6a0aed8-2cfe-0af3-dd6f-26e4f203be9e@redhat.com> (raw)
In-Reply-To: <20210607090203.133058-8-mlevitsk@redhat.com>

On 07/06/21 11:02, Maxim Levitsky wrote:
> +static int __set_sregs2(struct kvm_vcpu *vcpu, struct kvm_sregs2 *sregs2)
> +{
> +	int mmu_reset_needed = 0;
> +	bool valid_pdptrs = sregs2->flags & KVM_SREGS2_FLAGS_PDPTRS_VALID;
> +	int i, ret;
>   
> +	if (sregs2->flags & ~KVM_SREGS2_FLAGS_PDPTRS_VALID)
> +		return -EINVAL;
> +
> +	ret = __set_sregs_common(vcpu, (struct kvm_sregs *)sregs2,
> +				 &mmu_reset_needed, !valid_pdptrs);
> +	if (ret)
> +		return ret;
> +
> +	if (valid_pdptrs) {
> +		if (!is_pae_paging(vcpu))
> +			return -EINVAL;
> +		if (vcpu->arch.guest_state_protected)
> +			return -EINVAL;
> +		for (i = 0 ; i < 4 ; i++)
> +			kvm_pdptr_write(vcpu, i, sregs2->pdptrs[i]);
> +
> +		kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);
> +		mmu_reset_needed = 1;
> +	}
> +	if (mmu_reset_needed)
> +		kvm_mmu_reset_context(vcpu);
> +	return 0;
>   }

It's a bit nicer if the checks are done early:

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f20c7c06bd4a..c6f8fec78c53 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10248,22 +10248,23 @@ static int __set_sregs2(struct kvm_vcpu *vcpu, struct kvm_sregs2 *sregs2)
  {
         int mmu_reset_needed = 0;
         bool valid_pdptrs = sregs2->flags & KVM_SREGS2_FLAGS_PDPTRS_VALID;
+       bool pae = (sregs2->cr0 & X86_CR0_PG) && (sregs2->cr4 & X86_CR4_PAE) &&
+               !(sregs2->efer & EFER_LMA);
         int i, ret;
  
         if (sregs2->flags & ~KVM_SREGS2_FLAGS_PDPTRS_VALID)
                 return -EINVAL;
  
+       if (valid_pdptrs && (!pae || vcpu->arch.guest_state_protected))
+               return -EINVAL;
+
         ret = __set_sregs_common(vcpu, (struct kvm_sregs *)sregs2,
                                  &mmu_reset_needed, !valid_pdptrs);
         if (ret)
                 return ret;
  
         if (valid_pdptrs) {
-               if (!is_pae_paging(vcpu))
-                       return -EINVAL;
-               if (vcpu->arch.guest_state_protected)
-                       return -EINVAL;
-               for (i = 0 ; i < 4 ; i++)
+               for (i = 0; i < 4 ; i++)
                         kvm_pdptr_write(vcpu, i, sregs2->pdptrs[i]);
  
                 kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);

Paolo


  reply	other threads:[~2021-06-10 15:06 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-07  9:01 [PATCH v3 0/8] Introduce KVM_{GET|SET}_SREGS2 and fix PDPTR migration Maxim Levitsky
2021-06-07  9:01 ` [PATCH v3 1/8] KVM: nVMX: Drop obsolete (and pointless) pdptrs_changed() check Maxim Levitsky
2021-06-07  9:01 ` [PATCH v3 2/8] KVM: nSVM: Drop pointless pdptrs_changed() check on nested transition Maxim Levitsky
2021-06-07  9:01 ` [PATCH v3 3/8] KVM: x86: Always load PDPTRs on CR3 load for SVM w/o NPT and a PAE guest Maxim Levitsky
2021-06-07  9:01 ` [PATCH v3 4/8] KVM: nSVM: refactor the CR3 reload on migration Maxim Levitsky
2021-06-07  9:02 ` [PATCH v3 5/8] KVM: nVMX: delay loading of PDPTRs to KVM_REQ_GET_NESTED_STATE_PAGES Maxim Levitsky
2021-06-07  9:02 ` [PATCH v3 6/8] KVM: x86: introduce kvm_register_clear_available Maxim Levitsky
2021-06-07  9:02 ` [PATCH v3 7/8] KVM: x86: Introduce KVM_GET_SREGS2 / KVM_SET_SREGS2 Maxim Levitsky
2021-06-10 15:06   ` Paolo Bonzini [this message]
2021-06-07  9:02 ` [PATCH v3 8/8] KVM: x86: avoid loading PDPTRs after migration when possible Maxim Levitsky
2021-06-18 20:53   ` Sean Christopherson
2021-06-19  7:03     ` Paolo Bonzini
2021-06-20 22:25     ` Maxim Levitsky
2021-06-10 15:06 ` [PATCH v3 0/8] Introduce KVM_{GET|SET}_SREGS2 and fix PDPTR migration Paolo Bonzini

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