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From: Peter Xu <peterx@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Paul Mackerras" <paulus@ozlabs.org>,
	"Christian Borntraeger" <borntraeger@de.ibm.com>,
	"Janosch Frank" <frankja@linux.ibm.com>,
	"David Hildenbrand" <david@redhat.com>,
	"Cornelia Huck" <cohuck@redhat.com>,
	"Vitaly Kuznetsov" <vkuznets@redhat.com>,
	"Wanpeng Li" <wanpengli@tencent.com>,
	"Jim Mattson" <jmattson@google.com>,
	"Joerg Roedel" <joro@8bytes.org>, "Marc Zyngier" <maz@kernel.org>,
	"James Morse" <james.morse@arm.com>,
	"Julien Thierry" <julien.thierry.kdev@gmail.com>,
	"Suzuki K Poulose" <suzuki.poulose@arm.com>,
	linux-mips@vger.kernel.org, kvm@vger.kernel.org,
	kvm-ppc@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
	"Christoffer Dall" <christoffer.dall@arm.com>,
	"Philippe Mathieu-Daudé" <f4bug@amsat.org>
Subject: Re: [PATCH v5 14/19] KVM: Clean up local variable usage in __kvm_set_memory_region()
Date: Thu, 6 Feb 2020 14:36:40 -0500	[thread overview]
Message-ID: <20200206193640.GB700495@xz-x1> (raw)
In-Reply-To: <20200206192230.GE13067@linux.intel.com>

On Thu, Feb 06, 2020 at 11:22:30AM -0800, Sean Christopherson wrote:
> On Thu, Feb 06, 2020 at 02:06:41PM -0500, Peter Xu wrote:
> > On Tue, Jan 21, 2020 at 02:31:52PM -0800, Sean Christopherson wrote:
> > 
> > [...]
> > 
> > > @@ -1101,52 +1099,55 @@ int __kvm_set_memory_region(struct kvm *kvm,
> > >  	if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
> > >  		return -EINVAL;
> > >  
> > > -	slot = id_to_memslot(__kvm_memslots(kvm, as_id), id);
> > > -	base_gfn = mem->guest_phys_addr >> PAGE_SHIFT;
> > > -	npages = mem->memory_size >> PAGE_SHIFT;
> > > -
> > > -	if (npages > KVM_MEM_MAX_NR_PAGES)
> > > -		return -EINVAL;
> > > -
> > >  	/*
> > >  	 * Make a full copy of the old memslot, the pointer will become stale
> > >  	 * when the memslots are re-sorted by update_memslots().
> > >  	 */
> > > -	old = *slot;
> > > +	tmp = id_to_memslot(__kvm_memslots(kvm, as_id), id);
> > > +	old = *tmp;
> > > +	tmp = NULL;
> > 
> > Shall we keep this chunk to the patch where it will be used?  Other
> > than that, it looks good to me.
> 
> I assume you're talking about doing this instead of using @tmp?
> 
> 	old = *id_to_memslot(__kvm_memslots(kvm, as_id), id);

Yes.

> 
> It's obviously possible, but I really like resulting diff for
> __kvm_set_memory_region() in "KVM: Terminate memslot walks via used_slots"
> when tmp is used.
> 
> @@ -1104,8 +1203,13 @@ int __kvm_set_memory_region(struct kvm *kvm,
>          * when the memslots are re-sorted by update_memslots().
>          */
>         tmp = id_to_memslot(__kvm_memslots(kvm, as_id), id);
> -       old = *tmp;
> -       tmp = NULL;
> +       if (tmp) {
> +               old = *tmp;
> +               tmp = NULL;
> +       } else {
> +               memset(&old, 0, sizeof(old));
> +               old.id = id;
> +       }

I normally don't do that, for each patch I'll try to make it
consistent to itself, assuming that follow-up patches can be rejected.
I don't have strong opinion either, please feel free to keep them if
no one disagrees.

-- 
Peter Xu


  reply	other threads:[~2020-02-06 19:36 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-21 22:31 [PATCH v5 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
2020-01-21 22:31 ` [PATCH v5 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot Sean Christopherson
2020-02-05 21:49   ` Peter Xu
2020-02-05 23:55     ` Sean Christopherson
2020-02-06  2:00       ` Peter Xu
2020-02-06  2:17         ` Sean Christopherson
2020-02-06  2:58           ` Peter Xu
2020-02-06  5:05             ` Sean Christopherson
2020-01-21 22:31 ` [PATCH v5 02/19] KVM: Reinstall old memslots if arch preparation fails Sean Christopherson
2020-02-05 22:08   ` Peter Xu
2020-01-21 22:31 ` [PATCH v5 03/19] KVM: Don't free new memslot if allocation of said memslot fails Sean Christopherson
2020-02-05 22:28   ` Peter Xu
2020-01-21 22:31 ` [PATCH v5 04/19] KVM: PPC: Move memslot memory allocation into prepare_memory_region() Sean Christopherson
2020-02-05 22:41   ` Peter Xu
2020-01-21 22:31 ` [PATCH v5 05/19] KVM: x86: Allocate memslot resources during prepare_memory_region() Sean Christopherson
2020-01-21 22:31 ` [PATCH v5 06/19] KVM: Drop kvm_arch_create_memslot() Sean Christopherson
2020-02-05 22:45   ` Peter Xu
2020-01-21 22:31 ` [PATCH v5 07/19] KVM: Explicitly free allocated-but-unused dirty bitmap Sean Christopherson
2020-01-21 22:31 ` [PATCH v5 08/19] KVM: Refactor error handling for setting memory region Sean Christopherson
2020-02-05 22:48   ` Peter Xu
2020-01-21 22:31 ` [PATCH v5 09/19] KVM: Move setting of memslot into helper routine Sean Christopherson
2020-02-06 16:26   ` Peter Xu
2020-01-21 22:31 ` [PATCH v5 10/19] KVM: Drop "const" attribute from old memslot in commit_memory_region() Sean Christopherson
2020-02-06 16:26   ` Peter Xu
2020-01-21 22:31 ` [PATCH v5 11/19] KVM: x86: Free arrays for old memslot when moving memslot's base gfn Sean Christopherson
2020-01-21 22:31 ` [PATCH v5 12/19] KVM: Move memslot deletion to helper function Sean Christopherson
2020-02-06 16:14   ` Peter Xu
2020-02-06 16:28     ` Sean Christopherson
2020-02-06 16:51       ` Peter Xu
2020-02-07 17:59         ` Sean Christopherson
2020-02-07 18:07           ` Sean Christopherson
2020-02-07 18:17           ` Peter Xu
2020-01-21 22:31 ` [PATCH v5 13/19] KVM: Simplify kvm_free_memslot() and all its descendents Sean Christopherson
2020-02-06 16:29   ` Peter Xu
2020-01-21 22:31 ` [PATCH v5 14/19] KVM: Clean up local variable usage in __kvm_set_memory_region() Sean Christopherson
2020-02-06 19:06   ` Peter Xu
2020-02-06 19:22     ` Sean Christopherson
2020-02-06 19:36       ` Peter Xu [this message]
2020-01-21 22:31 ` [PATCH v5 15/19] KVM: Provide common implementation for generic dirty log functions Sean Christopherson
2020-02-06 20:02   ` Peter Xu
2020-02-06 21:21     ` Sean Christopherson
2020-02-06 21:41       ` Peter Xu
2020-02-07 19:45         ` Sean Christopherson
2020-02-08  0:18           ` Peter Xu
2020-02-08  0:42             ` Sean Christopherson
2020-02-08  0:53               ` Peter Xu
2020-02-08  1:29                 ` Sean Christopherson
2020-02-17 15:39                   ` Vitaly Kuznetsov
2020-02-18 17:10                     ` Sean Christopherson
2020-02-17 15:35           ` Vitaly Kuznetsov
2020-02-06 21:24   ` Peter Xu
2020-01-21 22:31 ` [PATCH v5 16/19] KVM: Ensure validity of memslot with respect to kvm_get_dirty_log() Sean Christopherson
2020-01-21 22:31 ` [PATCH v5 17/19] KVM: Terminate memslot walks via used_slots Sean Christopherson
2020-02-06 21:09   ` Peter Xu
2020-02-07 18:33     ` Sean Christopherson
2020-02-07 20:39       ` Peter Xu
2020-02-07 21:10         ` Sean Christopherson
2020-02-07 21:46           ` Peter Xu
2020-02-07 22:03             ` Sean Christopherson
2020-02-07 22:24               ` Peter Xu
2020-01-21 22:31 ` [PATCH v5 18/19] KVM: Dynamically size memslot array based on number of used slots Sean Christopherson
2020-02-06 22:12   ` Peter Xu
2020-02-07 15:38     ` Sean Christopherson
2020-02-07 16:05       ` Peter Xu
2020-02-07 16:15         ` Sean Christopherson
2020-02-07 16:37           ` Peter Xu
2020-02-07 16:47             ` Sean Christopherson
2020-01-21 22:31 ` [PATCH v5 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION Sean Christopherson
2020-02-06 22:30   ` Peter Xu
2020-02-06 23:11     ` Sean Christopherson

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