From: Sean Christopherson <seanjc@google.com>
To: Ackerley Tng <ackerleytng@google.com>
Cc: Chao Peng <chao.p.peng@linux.intel.com>,
vannapurve@google.com, x86@kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
pbonzini@redhat.com, vkuznets@redhat.com, wanpengli@tencent.com,
jmattson@google.com, joro@8bytes.org, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
hpa@zytor.com, shuah@kernel.org, yang.zhong@intel.com,
ricarkol@google.com, aaronlewis@google.com, wei.w.wang@intel.com,
kirill.shutemov@linux.intel.com, corbet@lwn.net,
hughd@google.com, jlayton@kernel.org, bfields@fieldses.org,
akpm@linux-foundation.org, yu.c.zhang@linux.intel.com,
jun.nakajima@intel.com, dave.hansen@intel.com,
michael.roth@amd.com, qperret@google.com, steven.price@arm.com,
ak@linux.intel.com, david@redhat.com, luto@kernel.org,
vbabka@suse.cz, marcorr@google.com, erdemaktas@google.com,
pgonda@google.com, nikunj@amd.com, diviness@google.com,
maz@kernel.org, dmatlack@google.com, axelrasmussen@google.com,
maciej.szmigiero@oracle.com, mizhang@google.com,
bgardon@google.com
Subject: Re: [V2 PATCH 0/6] KVM: selftests: selftests for fd-based private memory
Date: Wed, 8 Mar 2023 12:11:18 -0800 [thread overview]
Message-ID: <ZAjr5o2v00YrArcH@google.com> (raw)
In-Reply-To: <diqz356guhnx.fsf@ackerleytng-cloudtop.c.googlers.com>
On Wed, Mar 08, 2023, Ackerley Tng wrote:
> While I was working on the selftests I noticed that this could perhaps
> be improved:
>
> https://github.com/chao-p/linux/blob/ddd2c92b268a2fdc6158f82a6169ad1a57f2a01d/virt/kvm/kvm_main.c#L1035
>
> We should use a temporary variable to hold the result of fget(fd).
>
> As it is now, if the user provides any invalide fd, like -1,
> slot->restrictedmem.file would be overwritten and lost.
Meh, that can happen if and only if KVM has a bug elsehwere. If
slot->restrictedmem.file is anything but NULL, KVM is hosed. E.g. waiting to set
slot->restrictedmem.file until the very end wouldn't magically prevent a file
descriptor leak if slot->restrictedmem.file is non-NULL.
> We cannot update slot->restrictedmem.file until after the
> file_is_restrictedmem() check.
>
> For now there isn't a big problem because kvm_restrictedmem_bind() is
> only called on a new struct kvm_memory_slot, but I think this should be
> changed in case the function is used elsewhere in future.
Nah, if anything we could add
if (WARN_ON_ONCE(slot->restrictedmem.file))
return -EIO;
but I don't see the point. There's exactly one caller and the entire scheme
depends on binding the memslot to restricted memory when the memslot is created,
i.e. this would be but one of many changes if KVM were to allowed re-binding a
memslot.
next prev parent reply other threads:[~2023-03-08 20:11 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-05 23:23 [V2 PATCH 0/6] KVM: selftests: selftests for fd-based private memory Vishal Annapurve
2022-12-05 23:23 ` [V2 PATCH 1/6] KVM: x86: Add support for testing " Vishal Annapurve
2023-01-17 21:39 ` Sean Christopherson
2023-01-17 22:58 ` Vishal Annapurve
2022-12-05 23:23 ` [V2 PATCH 2/6] KVM: Selftests: Add support for " Vishal Annapurve
2023-01-17 21:46 ` Sean Christopherson
2023-01-17 23:03 ` Vishal Annapurve
2022-12-05 23:23 ` [V2 PATCH 3/6] KVM: selftests: x86: Add IS_ALIGNED/IS_PAGE_ALIGNED helpers Vishal Annapurve
2023-01-17 21:48 ` Sean Christopherson
2023-01-17 23:06 ` Vishal Annapurve
2022-12-05 23:23 ` [V2 PATCH 4/6] KVM: selftests: x86: Add helpers to execute VMs with private memory Vishal Annapurve
2023-01-17 22:06 ` Sean Christopherson
2023-01-17 22:51 ` Sean Christopherson
2022-12-05 23:23 ` [V2 PATCH 5/6] KVM: selftests: Add get_free_huge_2m_pages Vishal Annapurve
2023-01-17 22:12 ` Sean Christopherson
2022-12-05 23:23 ` [V2 PATCH 6/6] KVM: selftests: x86: Add selftest for private memory Vishal Annapurve
2023-01-18 0:53 ` Sean Christopherson
2023-01-18 1:09 ` [V2 PATCH 0/6] KVM: selftests: selftests for fd-based " Sean Christopherson
2023-01-18 3:11 ` Vishal Annapurve
2023-02-10 19:59 ` Vishal Annapurve
2023-02-22 2:50 ` Chao Peng
2023-03-06 18:21 ` Ackerley Tng
2023-03-07 2:18 ` Chao Peng
2023-03-08 1:59 ` Ackerley Tng
2023-03-08 20:11 ` Sean Christopherson [this message]
2023-01-18 11:25 ` Kirill A. Shutemov
2023-01-18 17:17 ` Sean Christopherson
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