KVM: x86: hyper-v: Check access to HVCALL_NOTIFY_LONG_SPIN_WAIT hypercall

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TLFS6.0b states that partition issuing HVCALL_NOTIFY_LONG_SPIN_WAIT must
posess 'UseHypercallForLongSpinWait' privilege but there's no
corresponding feature bit. Instead, we have "Recommended number of attempts
to retry a spinlock failure before notifying the hypervisor about the
failures. 0xFFFFFFFF indicates never notify." Use this to check access to
the hypercall. Also, check against zero as the corresponding CPUID must
be set (and '0' attempts before re-try is weird anyway).

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-22-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

...

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Vitaly Kuznetsov 2021-05-21 11:51:55 +02:00 • committed by Paolo Bonzini

parent 4ad81a9111

commit 34ef7d7b9c

1 changed files with 11 additions and 0 deletions

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arch/x86/kvm/hyperv.c

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