From: Peter Xu <peterx@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
Andrew Jones <drjones@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
"Michael S . Tsirkin" <mst@redhat.com>,
Jason Wang <jasowang@redhat.com>,
Kevin Tian <kevin.tian@intel.com>
Subject: Re: [PATCH v10 03/14] KVM: X86: Don't track dirty for KVM_SET_[TSS_ADDR|IDENTITY_MAP_ADDR]
Date: Fri, 3 Jul 2020 15:02:47 -0400 [thread overview]
Message-ID: <20200703190247.GG6677@xz-x1> (raw)
In-Reply-To: <20200703000557.GM3575@linux.intel.com>
On Thu, Jul 02, 2020 at 05:05:57PM -0700, Sean Christopherson wrote:
> > /* Set up identity-mapping pagetable for EPT in real mode */
> > for (i = 0; i < PT32_ENT_PER_PAGE; i++) {
> > tmp = (i << 22) + (_PAGE_PRESENT | _PAGE_RW | _PAGE_USER |
> > _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_PSE);
> > - r = kvm_write_guest_page(kvm, identity_map_pfn,
> > - &tmp, i * sizeof(tmp), sizeof(tmp));
> > - if (r < 0)
> > + r = __copy_to_user(uaddr + i * sizeof(tmp), &tmp, sizeof(tmp));
> > + if (r) {
> > + r = -EFAULT;
>
> Another case where capturing the result is unnecessary. I don't have a
> preference as to whether the result of __copy_{to,from}_user() is returned
> directly or morphed to -EFAULT, but we should be consistent, especially
> within a single patch.
OK, I'll clean all these __copy_to_user() callers in the next version.
>
> > goto out;
> > + }
> > }
> > kvm_vmx->ept_identity_pagetable_done = true;
> >
> > @@ -3532,19 +3525,22 @@ static void seg_setup(int seg)
> > static int alloc_apic_access_page(struct kvm *kvm)
> > {
> > struct page *page;
> > - int r = 0;
> > + void __user *r;
> > + int ret = 0;
> >
> > mutex_lock(&kvm->slots_lock);
> > if (kvm->arch.apic_access_page_done)
> > goto out;
> > r = __x86_set_memory_region(kvm, APIC_ACCESS_PAGE_PRIVATE_MEMSLOT,
> > APIC_DEFAULT_PHYS_BASE, PAGE_SIZE);
>
> Naming the new 'void __user *hva' would yield a smaller differ and would
> probably help readers in the future.
OK.
> > } else {
> > - if (!slot || !slot->npages)
> > - return 0;
> > -
> > /*
> > * Stuff a non-canonical value to catch use-after-delete. This
> > * ends up being 0 on 32-bit KVM, but there's no better
> > * alternative.
> > */
> > hva = (unsigned long)(0xdeadull << 48);
> > +
> > + if (!slot || !slot->npages)
> > + return (void __user *)hva;
>
> My clever shenanigans got discarded, so this weirdness happily is gone.
I'll see what I get when I rebase. This series is easy to encounter conflicts
during previous rebases for misterious reasons. I guess I'll just repost less
frequently so I suffer less from rebase too. :)
Thanks.
--
Peter Xu
next prev parent reply other threads:[~2020-07-03 19:02 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-01 11:59 [PATCH v10 00/14] KVM: Dirty ring interface Peter Xu
2020-06-01 11:59 ` [PATCH v10 01/14] KVM: X86: Change parameter for fast_page_fault tracepoint Peter Xu
2020-06-01 11:59 ` [PATCH v10 02/14] KVM: Cache as_id in kvm_memory_slot Peter Xu
2020-07-02 23:08 ` Sean Christopherson
2020-07-03 18:41 ` Peter Xu
2020-07-07 6:17 ` Sean Christopherson
2020-07-07 19:50 ` Peter Xu
2020-07-07 19:56 ` Sean Christopherson
2020-07-07 20:15 ` Peter Xu
2020-07-07 20:26 ` Sean Christopherson
2020-07-07 20:38 ` Peter Xu
2020-06-01 11:59 ` [PATCH v10 03/14] KVM: X86: Don't track dirty for KVM_SET_[TSS_ADDR|IDENTITY_MAP_ADDR] Peter Xu
2020-07-03 0:05 ` Sean Christopherson
2020-07-03 19:02 ` Peter Xu [this message]
2020-06-01 11:59 ` [PATCH v10 04/14] KVM: Pass in kvm pointer into mark_page_dirty_in_slot() Peter Xu
2020-06-01 11:59 ` [PATCH v10 05/14] KVM: X86: Implement ring-based dirty memory tracking Peter Xu
2020-06-01 11:59 ` [PATCH v10 06/14] KVM: Make dirty ring exclusive to dirty bitmap log Peter Xu
2020-06-01 11:59 ` [PATCH v10 07/14] KVM: Don't allocate dirty bitmap if dirty ring is enabled Peter Xu
2020-06-01 11:59 ` [PATCH v10 08/14] KVM: selftests: Always clear dirty bitmap after iteration Peter Xu
2020-06-01 11:59 ` [PATCH v10 09/14] KVM: selftests: Sync uapi/linux/kvm.h to tools/ Peter Xu
2020-06-01 11:59 ` [PATCH v10 10/14] KVM: selftests: Use a single binary for dirty/clear log test Peter Xu
2020-06-01 11:59 ` [PATCH v10 11/14] KVM: selftests: Introduce after_vcpu_run hook for dirty " Peter Xu
2020-06-01 11:59 ` [PATCH v10 12/14] KVM: selftests: Add dirty ring buffer test Peter Xu
2020-06-01 12:05 ` [PATCH v10 13/14] KVM: selftests: Let dirty_log_test async for dirty ring test Peter Xu
2020-06-01 12:05 ` [PATCH v10 14/14] KVM: selftests: Add "-c" parameter to dirty log test Peter Xu
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