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From: Paolo Bonzini <pbonzini@redhat.com>
To: Emanuele Giuseppe Esposito <eesposit@redhat.com>, kvm@vger.kernel.org
Cc: Maxim Levitsky <mlevitsk@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/2] nSVM: introduce struct vmcb_ctrl_area_cached
Date: Tue, 28 Sep 2021 18:14:49 +0200	[thread overview]
Message-ID: <05425bd8-46dc-f136-fbe0-52f42351aea1@redhat.com> (raw)
In-Reply-To: <20210917124956.2042052-2-eesposit@redhat.com>

On 17/09/21 14:49, Emanuele Giuseppe Esposito wrote:
> +static inline bool vmcb_is_intercept_cached(struct vmcb_ctrl_area_cached *control, u32 bit)
> +{
> +	return vmcb_is_intercept((struct vmcb_control_area *) control,
> +				 bit);
> +}
> +

This is quite dangerous, because it expects that the offset is the same 
between vmcb_control_area and vmcb_ctrl_area_cached.  You can just 
duplicate the implementation (which is essentially just a test_bit), and 
call the function

static inline bool vmcb12_is_intercept(struct kvm_vcpu *vcpu, u32 bit)

Likewise, nested_vmcb_check_controls can just take the vcpu since you 
moved nested_load_control_from_vmcb12 earlier.

Finally, copy_vmcb_control_area can be inlined, and its caller 
nested_load_control_from_vmcb12 can stop copying the ASID.  There is 
only one call to it since commit 4995a3685f1b ("KVM: SVM: Use a separate 
vmcb for the nested L2 guest", 2021-03-15).

Thanks,

Paolo


  reply	other threads:[~2021-09-28 16:14 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-17 12:49 [RFC PATCH 0/2] KVM: nSVM: use vmcb_ctrl_area_cached instead Emanuele Giuseppe Esposito
2021-09-17 12:49 ` [RFC PATCH 1/2] nSVM: introduce struct vmcb_ctrl_area_cached Emanuele Giuseppe Esposito
2021-09-28 16:14   ` Paolo Bonzini [this message]
2021-09-17 12:49 ` [RFC PATCH 2/2] nSVM: use vmcb_ctrl_area_cached instead of vmcb_control_area in svm_nested_state Emanuele Giuseppe Esposito

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