On Mon, Dec 13, 2021 at 10:50:12AM +0100, Vitaly Kuznetsov wrote:
> From: Sean Christopherson <seanjc@xxxxxxxxxx>
>
> 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: 214ff83d4473 ("KVM: x86: hyperv: implement PV IPI send hypercalls")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> Message-Id: <20211207220926.718794-2-seanjc@xxxxxxxxxx>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> ---
> arch/x86/kvm/hyperv.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
Both now queued up, thanks.
greg k-h
