linux-kernel - Re: [PATCH RFC v8 04/56] KVM: Add HVA range operator

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Message-ID: <20230220233709.00006dfc@gmail.com>
Date:   Mon, 20 Feb 2023 23:37:09 +0200
From:   Zhi Wang <zhi.wang.linux@...il.com>
To:     Michael Roth <michael.roth@....com>
Cc:     <kvm@...r.kernel.org>, <linux-coco@...ts.linux.dev>,
        <linux-mm@...ck.org>, <linux-crypto@...r.kernel.org>,
        <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <jroedel@...e.de>,
        <thomas.lendacky@....com>, <hpa@...or.com>, <ardb@...nel.org>,
        <pbonzini@...hat.com>, <seanjc@...gle.com>, <vkuznets@...hat.com>,
        <jmattson@...gle.com>, <luto@...nel.org>,
        <dave.hansen@...ux.intel.com>, <slp@...hat.com>,
        <pgonda@...gle.com>, <peterz@...radead.org>,
        <srinivas.pandruvada@...ux.intel.com>, <rientjes@...gle.com>,
        <dovmurik@...ux.ibm.com>, <tobin@....com>, <bp@...en8.de>,
        <vbabka@...e.cz>, <kirill@...temov.name>, <ak@...ux.intel.com>,
        <tony.luck@...el.com>, <marcorr@...gle.com>,
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        <alpergun@...gle.com>, <dgilbert@...hat.com>, <jarkko@...nel.org>,
        <ashish.kalra@....com>, <nikunj.dadhania@....com>,
        Vishal Annapurve <vannapurve@...gle.com>
Subject: Re: [PATCH RFC v8 04/56] KVM: Add HVA range operator

On Mon, 20 Feb 2023 12:37:55 -0600
Michael Roth <michael.roth@....com> wrote:

> From: Vishal Annapurve <vannapurve@...gle.com>
> 
> Introduce HVA range operator so that other KVM subsystems
> can operate on HVA range.
> 
> Signed-off-by: Vishal Annapurve <vannapurve@...gle.com>
> [mdr: minor checkpatch alignment fixups]
> Signed-off-by: Michael Roth <michael.roth@....com>
> ---
>  include/linux/kvm_host.h |  6 +++++
>  virt/kvm/kvm_main.c      | 48 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 54 insertions(+)
> 
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 4d542060cd93..c615650ed256 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1402,6 +1402,12 @@ void kvm_mmu_invalidate_begin(struct kvm *kvm);
>  void kvm_mmu_invalidate_range_add(struct kvm *kvm, gfn_t start, gfn_t end);
>  void kvm_mmu_invalidate_end(struct kvm *kvm);
>  
> +typedef int (*kvm_hva_range_op_t)(struct kvm *kvm,
> +				struct kvm_gfn_range *range, void *data);
> +
> +int kvm_vm_do_hva_range_op(struct kvm *kvm, unsigned long hva_start,
> +			   unsigned long hva_end, kvm_hva_range_op_t handler, void *data);
> +
>  long kvm_arch_dev_ioctl(struct file *filp,
>  			unsigned int ioctl, unsigned long arg);
>  long kvm_arch_vcpu_ioctl(struct file *filp,
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index f7e00593cc5d..4ccd655dd5af 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -642,6 +642,54 @@ static __always_inline int __kvm_handle_hva_range(struct kvm *kvm,
>  	return (int)ret;
>  }
>  

Below function seems a reduced duplicate of __kvm_handle_hva_range()
in virt/kvm/kvm_main.c. It would be nice to factor __kvm_handle_hva_range().

> +int kvm_vm_do_hva_range_op(struct kvm *kvm, unsigned long hva_start,
> +			   unsigned long hva_end, kvm_hva_range_op_t handler, void *data)
> +{
> +	int ret = 0;
> +	struct kvm_gfn_range gfn_range;
> +	struct kvm_memory_slot *slot;
> +	struct kvm_memslots *slots;
> +	int i, idx;
> +
> +	if (WARN_ON_ONCE(hva_end <= hva_start))
> +		return -EINVAL;
> +
> +	idx = srcu_read_lock(&kvm->srcu);
> +
> +	for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) {
> +		struct interval_tree_node *node;
> +
> +		slots = __kvm_memslots(kvm, i);
> +		kvm_for_each_memslot_in_hva_range(node, slots,
> +						  hva_start, hva_end - 1) {
> +			unsigned long start, end;
> +
> +			slot = container_of(node, struct kvm_memory_slot,
> +					    hva_node[slots->node_idx]);
> +			start = max(hva_start, slot->userspace_addr);
> +			end = min(hva_end, slot->userspace_addr +
> +						  (slot->npages << PAGE_SHIFT));
> +
> +			/*
> +			 * {gfn(page) | page intersects with [hva_start, hva_end)} =
> +			 * {gfn_start, gfn_start+1, ..., gfn_end-1}.
> +			 */
> +			gfn_range.start = hva_to_gfn_memslot(start, slot);
> +			gfn_range.end = hva_to_gfn_memslot(end + PAGE_SIZE - 1, slot);
> +			gfn_range.slot = slot;
> +
> +			ret = handler(kvm, &gfn_range, data);
> +			if (ret)
> +				goto e_ret;
> +		}
> +	}
> +
> +e_ret:
> +	srcu_read_unlock(&kvm->srcu, idx);
> +
> +	return ret;
> +}
> +
>  static __always_inline int kvm_handle_hva_range(struct mmu_notifier *mn,
>  						unsigned long start,
>  						unsigned long end,