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author | Sean Christopherson <seanjc@google.com> | 2021-10-09 05:11:56 +0300 |
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committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-12-08 12:24:46 +0300 |
commit | 6f390916c4fb359507d9ac4bf1b28a4f8abee5c0 (patch) | |
tree | e0966bd41f639b4b128a11666bfc8b14459f30f2 /net/phonet | |
parent | 91b01895071770ed0c256869d0f94d69a2fb8ecf (diff) | |
download | linux-6f390916c4fb359507d9ac4bf1b28a4f8abee5c0.tar.xz |
KVM: s390: Ensure kvm_arch_no_poll() is read once when blocking vCPU
Wrap s390's halt_poll_max_steal with READ_ONCE and snapshot the result of
kvm_arch_no_poll() in kvm_vcpu_block() to avoid a mostly-theoretical,
largely benign bug on s390 where the result of kvm_arch_no_poll() could
change due to userspace modifying halt_poll_max_steal while the vCPU is
blocking. The bug is largely benign as it will either cause KVM to skip
updating halt-polling times (no_poll toggles false=>true) or to update
halt-polling times with a slightly flawed block_ns.
Note, READ_ONCE is unnecessary in the current code, add it in case the
arch hook is ever inlined, and to provide a hint that userspace can
change the param at will.
Fixes: 8b905d28ee17 ("KVM: s390: provide kvm_arch_no_poll function")
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-4-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'net/phonet')
0 files changed, 0 insertions, 0 deletions