From: Sean Christopherson <seanjc@google.com>
To: Paul Durrant <paul@xen.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Jonathan Corbet <corbet@lwn.net>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
David Woodhouse <dwmw2@infradead.org>,
Shuah Khan <shuah@kernel.org>,
kvm@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v12 11/20] KVM: xen: allow shared_info to be mapped by fixed HVA
Date: Tue, 6 Feb 2024 20:10:10 -0800 [thread overview]
Message-ID: <ZcMCogbbVKuTIXWJ@google.com> (raw)
In-Reply-To: <20240115125707.1183-12-paul@xen.org>
On Mon, Jan 15, 2024, Paul Durrant wrote:
> @@ -638,20 +637,32 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data)
> }
> break;
>
> - case KVM_XEN_ATTR_TYPE_SHARED_INFO: {
> + case KVM_XEN_ATTR_TYPE_SHARED_INFO:
> + case KVM_XEN_ATTR_TYPE_SHARED_INFO_HVA: {
> int idx;
>
> mutex_lock(&kvm->arch.xen.xen_lock);
>
> idx = srcu_read_lock(&kvm->srcu);
>
> - if (data->u.shared_info.gfn == KVM_XEN_INVALID_GFN) {
> - kvm_gpc_deactivate(&kvm->arch.xen.shinfo_cache);
> - r = 0;
> + if (data->type == KVM_XEN_ATTR_TYPE_SHARED_INFO) {
> + if (data->u.shared_info.gfn == KVM_XEN_INVALID_GFN) {
> + kvm_gpc_deactivate(&kvm->arch.xen.shinfo_cache);
> + r = 0;
> + } else {
> + r = kvm_gpc_activate(&kvm->arch.xen.shinfo_cache,
> + gfn_to_gpa(data->u.shared_info.gfn),
> + PAGE_SIZE);
> + }
> } else {
> - r = kvm_gpc_activate(&kvm->arch.xen.shinfo_cache,
> - gfn_to_gpa(data->u.shared_info.gfn),
> - PAGE_SIZE);
> + if (data->u.shared_info.hva == 0) {
I know I said I don't care about the KVM Xen ABI, but I still think using '0' as
"invalid" is ridiculous.
More importantly, this code needs to check that HVA is a userspace pointer.
Because __kvm_set_memory_region() performs the address checks, KVM assumes any
hva that it gets out of a memslot, i.e. from a gfn, is a safe userspace address.
kvm_is_error_hva() will catch most addresses, but I'm pretty sure there's still
a small window where userspace could use this to write kernel memory.
> + kvm_gpc_deactivate(&kvm->arch.xen.shinfo_cache);
> + r = 0;
> + } else {
> + r = kvm_gpc_activate_hva(&kvm->arch.xen.shinfo_cache,
> + data->u.shared_info.hva,
> + PAGE_SIZE);
> + }
next prev parent reply other threads:[~2024-02-07 4:10 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-15 12:56 [PATCH v12 00/20] KVM: xen: update shared_info and vcpu_info handling Paul Durrant
2024-01-15 12:56 ` [PATCH v12 01/20] KVM: pfncache: Add a map helper function Paul Durrant
2024-01-15 12:56 ` [PATCH v12 02/20] KVM: pfncache: remove unnecessary exports Paul Durrant
2024-01-15 12:56 ` [PATCH v12 03/20] KVM: xen: mark guest pages dirty with the pfncache lock held Paul Durrant
2024-02-07 3:17 ` Sean Christopherson
2024-02-07 3:26 ` David Woodhouse
2024-02-07 15:15 ` Sean Christopherson
2024-02-07 8:48 ` Paul Durrant
2024-01-15 12:56 ` [PATCH v12 04/20] KVM: pfncache: add a mark-dirty helper Paul Durrant
2024-02-07 3:20 ` Sean Christopherson
2024-02-07 8:47 ` Paul Durrant
2024-02-09 15:58 ` Sean Christopherson
2024-02-09 16:05 ` Paul Durrant
2024-01-15 12:56 ` [PATCH v12 05/20] KVM: pfncache: remove KVM_GUEST_USES_PFN usage Paul Durrant
2024-01-15 12:56 ` [PATCH v12 06/20] KVM: pfncache: stop open-coding offset_in_page() Paul Durrant
2024-01-15 12:56 ` [PATCH v12 07/20] KVM: pfncache: include page offset in uhva and use it consistently Paul Durrant
2024-01-15 12:56 ` [PATCH v12 08/20] KVM: pfncache: allow a cache to be activated with a fixed (userspace) HVA Paul Durrant
2024-02-07 4:03 ` Sean Christopherson
2024-02-07 4:13 ` David Woodhouse
2024-02-14 16:01 ` Sean Christopherson
2024-02-14 16:09 ` Paul Durrant
2024-02-14 15:21 ` Paul Durrant
2024-02-14 16:20 ` Sean Christopherson
2024-02-14 16:33 ` Paul Durrant
2024-01-15 12:56 ` [PATCH v12 09/20] KVM: xen: separate initialization of shared_info cache and content Paul Durrant
2024-01-15 12:56 ` [PATCH v12 10/20] KVM: xen: re-initialize shared_info if guest (32/64-bit) mode is set Paul Durrant
2024-01-15 12:56 ` [PATCH v12 11/20] KVM: xen: allow shared_info to be mapped by fixed HVA Paul Durrant
2024-02-07 4:10 ` Sean Christopherson [this message]
2024-02-07 8:53 ` Paul Durrant
2024-02-08 8:52 ` Paul Durrant
2024-02-08 16:48 ` Sean Christopherson
2024-02-08 16:51 ` Paul Durrant
2024-02-08 17:26 ` David Woodhouse
2024-02-09 16:01 ` Sean Christopherson
2024-01-15 12:56 ` [PATCH v12 12/20] KVM: xen: allow vcpu_info " Paul Durrant
2024-01-15 12:57 ` [PATCH v12 13/20] KVM: selftests / xen: map shared_info using HVA rather than GFN Paul Durrant
2024-02-07 4:14 ` Sean Christopherson
2024-02-07 8:54 ` Paul Durrant
2024-02-07 14:58 ` Sean Christopherson
2024-01-15 12:57 ` [PATCH v12 14/20] KVM: selftests / xen: re-map vcpu_info using HVA rather than GPA Paul Durrant
2024-01-15 12:57 ` [PATCH v12 15/20] KVM: xen: advertize the KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA capability Paul Durrant
2024-01-15 12:57 ` [PATCH v12 16/20] KVM: xen: split up kvm_xen_set_evtchn_fast() Paul Durrant
2024-01-15 12:57 ` [PATCH v12 17/20] KVM: xen: don't block on pfncache locks in kvm_xen_set_evtchn_fast() Paul Durrant
2024-02-07 4:17 ` Sean Christopherson
2024-02-07 4:21 ` David Woodhouse
2024-01-15 12:57 ` [PATCH v12 18/20] KVM: pfncache: check the need for invalidation under read lock first Paul Durrant
2024-02-07 4:22 ` Sean Christopherson
2024-02-07 4:27 ` David Woodhouse
2024-02-07 4:47 ` Sean Christopherson
2024-02-07 4:59 ` David Woodhouse
2024-02-07 15:10 ` Sean Christopherson
2024-01-15 12:57 ` [PATCH v12 19/20] KVM: xen: allow vcpu_info content to be 'safely' copied Paul Durrant
2024-01-15 12:57 ` [PATCH v12 20/20] KVM: pfncache: rework __kvm_gpc_refresh() to fix locking issues Paul Durrant
2024-01-25 15:03 ` [PATCH v12 00/20] KVM: xen: update shared_info and vcpu_info handling Paul Durrant
2024-01-25 20:07 ` David Woodhouse
2024-01-26 1:19 ` Sean Christopherson
2024-02-02 17:37 ` Paul Durrant
2024-02-02 22:03 ` Sean Christopherson
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