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Commit 2fb8e426 authored by Sean Christopherson's avatar Sean Christopherson Committed by Greg Kroah-Hartman
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KVM: x86: Ignore sparse banks size for an "all CPUs", non-sparse IPI req 



commit 3244867af8c065e51969f1bffe732d3ebfd9a7d2 upstream.

Do not bail early if there are no bits set in the sparse banks for a
non-sparse, a.k.a. "all CPUs", IPI request.  Per the Hyper-V spec, it is
legal to have a variable length of '0', e.g. VP_SET's BankContents in
this case, if the request can be serviced without the extra info.

  It is possible that for a given invocation of a hypercall that does
  accept variable sized input headers that all the header input fits
  entirely within the fixed size header. In such cases the variable sized
  input header is zero-sized and the corresponding bits in the hypercall
  input should be set to zero.

Bailing early results in KVM failing to send IPIs to all CPUs as expected
by the guest.

Fixes: 214ff83d ("KVM: x86: hyperv: implement PV IPI send hypercalls")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Reviewed-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20211207220926.718794-2-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 46735995

arch/x86/kvm/hyperv.c

+5 −2
Original line number Diff line number Diff line
@@ -1501,11 +1501,13 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *current_vcpu, u64 ingpa, u64 outgpa, 


		all_cpus = send_ipi_ex.vp_set.format == HV_GENERIC_SET_ALL;



		if (all_cpus)

			goto check_and_send_ipi;



		if (!sparse_banks_len)

			goto ret_success;



		if (!all_cpus &&

		    kvm_read_guest(kvm,

		if (kvm_read_guest(kvm,

				   ingpa + offsetof(struct hv_send_ipi_ex,

						    vp_set.bank_contents),

				   sparse_banks,
@@ -1513,6 +1515,7 @@ static u64 kvm_hv_send_ipi(struct kvm_vcpu *current_vcpu, u64 ingpa, u64 outgpa, 
			return HV_STATUS_INVALID_HYPERCALL_INPUT;

	}



check_and_send_ipi:

	if ((vector < HV_IPI_LOW_VECTOR) || (vector > HV_IPI_HIGH_VECTOR))

		return HV_STATUS_INVALID_HYPERCALL_INPUT;