From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Sean Christopherson <seanjc@google.com>
Cc: Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-hyperv@vger.kernel.org,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
Ajay Garg <ajaygargnsit@gmail.com>,
Paolo Bonzini <pbonzini@redhat.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Wei Liu <wei.liu@kernel.org>, Dexuan Cui <decui@microsoft.com>,
Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH v3 7/8] KVM: x86: Reject fixeds-size Hyper-V hypercalls with non-zero "var_cnt"
Date: Thu, 09 Dec 2021 10:55:50 +0100 [thread overview]
Message-ID: <87lf0u3xw9.fsf@redhat.com> (raw)
In-Reply-To: <20211207220926.718794-8-seanjc@google.com>
Sean Christopherson <seanjc@google.com> writes:
> Reject Hyper-V hypercalls if the guest specifies a non-zero variable size
> header (var_cnt in KVM) for a hypercall that has a fixed header size.
> Per the TLFS:
>
> It is illegal to specify a non-zero variable header size for a
> hypercall that is not explicitly documented as accepting variable sized
> input headers. In such a case the hypercall will result in a return
> code of HV_STATUS_INVALID_HYPERCALL_INPUT.
>
> Note, at least some of the various DEBUG commands likely aren't allowed
> to use variable size headers, but the TLFS documentation doesn't clearly
> state what is/isn't allowed. Omit them for now to avoid unnecessary
> breakage.
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/kvm/hyperv.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index f33a5e890048..522ccd2f0db4 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -2250,14 +2250,14 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
>
> switch (hc.code) {
> case HVCALL_NOTIFY_LONG_SPIN_WAIT:
> - if (unlikely(hc.rep)) {
> + if (unlikely(hc.rep || hc.var_cnt)) {
> ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
> break;
> }
> kvm_vcpu_on_spin(vcpu, true);
> break;
> case HVCALL_SIGNAL_EVENT:
> - if (unlikely(hc.rep)) {
> + if (unlikely(hc.rep || hc.var_cnt)) {
> ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
> break;
> }
> @@ -2267,7 +2267,7 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
> fallthrough; /* maybe userspace knows this conn_id */
> case HVCALL_POST_MESSAGE:
> /* don't bother userspace if it has no way to handle it */
> - if (unlikely(hc.rep || !to_hv_synic(vcpu)->active)) {
> + if (unlikely(hc.rep || hc.var_cnt || !to_hv_synic(vcpu)->active)) {
> ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
> break;
> }
> @@ -2280,14 +2280,14 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
> kvm_hv_hypercall_complete_userspace;
> return 0;
> case HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST:
> - if (unlikely(!hc.rep_cnt || hc.rep_idx)) {
> + if (unlikely(!hc.rep_cnt || hc.rep_idx || hc.var_cnt)) {
> ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
> break;
> }
> ret = kvm_hv_flush_tlb(vcpu, &hc, false);
> break;
> case HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE:
> - if (unlikely(hc.rep)) {
> + if (unlikely(hc.rep || hc.var_cnt)) {
> ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
> break;
> }
> @@ -2308,7 +2308,7 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
> ret = kvm_hv_flush_tlb(vcpu, &hc, true);
> break;
> case HVCALL_SEND_IPI:
> - if (unlikely(hc.rep)) {
> + if (unlikely(hc.rep || hc.var_cnt)) {
> ret = HV_STATUS_INVALID_HYPERCALL_INPUT;
> break;
> }
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
--
Vitaly
next prev parent reply other threads:[~2021-12-09 9:55 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-07 22:09 [PATCH v3 0/8] KVM: x86: Hyper-V hypercall fix and cleanups Sean Christopherson
2021-12-07 22:09 ` [PATCH v3 1/8] KVM: x86: Ignore sparse banks size for an "all CPUs", non-sparse IPI req Sean Christopherson
2021-12-09 11:19 ` Paolo Bonzini
2021-12-07 22:09 ` [PATCH v3 2/8] KVM: x86: Get the number of Hyper-V sparse banks from the VARHEAD field Sean Christopherson
2021-12-07 22:09 ` [PATCH v3 3/8] KVM: x86: Refactor kvm_hv_flush_tlb() to reduce indentation Sean Christopherson
2021-12-07 22:09 ` [PATCH v3 4/8] KVM: x86: Add a helper to get the sparse VP_SET for IPIs and TLB flushes Sean Christopherson
2021-12-07 22:09 ` [PATCH v3 5/8] KVM: x86: Don't bother reading sparse banks that end up being ignored Sean Christopherson
2021-12-07 22:09 ` [PATCH v3 6/8] KVM: x86: Shove vp_bitmap handling down into sparse_set_to_vcpu_mask() Sean Christopherson
2021-12-07 22:09 ` [PATCH v3 7/8] KVM: x86: Reject fixeds-size Hyper-V hypercalls with non-zero "var_cnt" Sean Christopherson
2021-12-09 9:55 ` Vitaly Kuznetsov [this message]
2021-12-07 22:09 ` [PATCH v3 8/8] KVM: x86: Add checks for reserved-to-zero Hyper-V hypercall fields Sean Christopherson
2022-02-01 13:47 ` [PATCH v3 0/8] KVM: x86: Hyper-V hypercall fix and cleanups Paolo Bonzini
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