linux-kernel - Re: [PART2 PATCH v3 10/11] svm: Introduce AMD IOMMU avic_ga_log

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Message-ID: <20160711190932.GB1375@potion>
Date:	Mon, 11 Jul 2016 21:09:33 +0200
From:	Radim Krčmář <rkrcmar@...hat.com>
To:	Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Cc:	joro@...tes.org, pbonzini@...hat.com, alex.williamson@...hat.com,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	sherry.hurwitz@....com
Subject: Re: [PART2 PATCH v3 10/11] svm: Introduce AMD IOMMU
 avic_ga_log_notifier

2016-07-11 05:11-0500, Suravee Suthikulpanit:
> From: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
> 
> This patch introduces avic_ga_log_notifier, which will be called
> by IOMMU driver whenever it handles the Guest vAPIC (GA) log entry.
> 
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
> ---
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> @@ -928,6 +930,45 @@ static void svm_disable_lbrv(struct vcpu_svm *svm)
> +static int avic_ga_log_notifier(int avic_tag, int vcpu_id, int vec)
> +{
> +	unsigned long flags;
> +	struct kvm_arch *ka = NULL;
> +	struct kvm_vcpu *vcpu = NULL;
> +	struct vcpu_svm *svm = NULL;
> +
> +	pr_debug("SVM: %s: avic_tag=%#x, vcpu_id=%#x, vec=%#x\n",
> +		 __func__, avic_tag, vcpu_id, vec);
> +
> +	spin_lock_irqsave(&svm_vm_data_hash_lock, flags);
> +	hash_for_each_possible(svm_vm_data_hash, ka, hnode, avic_tag) {
> +		struct kvm *kvm = container_of(ka, struct kvm, arch);

iommu_handle_ga_guest_nr_entry(), the caller, already performed a hash
lookup to get ir_data.  Cannot we store the vcpu pointer in ir_data, to
avoid a second hash lookup and a vcpu lookup?

Thanks.