KVM: x86: obey KVM_X86_QUIRK_CD_NW_CLEARED in kvm_set_cr0()
Commit b18d5431 ("KVM: x86: fix CR0.CD virtualization") was technically correct, but it broke OVMF guests by slowing down various parts of the firmware. Commit fb279950 ("KVM: vmx: obey KVM_QUIRK_CD_NW_CLEARED") quirked the first function modified by b18d5431, vmx_get_mt_mask(), for OVMF's sake. This restored the speed of the OVMF code that runs before PlatformPei (including the memory intensive LZMA decompression in SEC). This patch extends the quirk to the second function modified by b18d5431, kvm_set_cr0(). It eliminates the intrusive slowdown that hits the EFI_MP_SERVICES_PROTOCOL implementation of edk2's UefiCpuPkg/CpuDxe -- which is built into OVMF --, when CpuDxe starts up all APs at once for initialization, in order to count them. We also carry over the kvm_arch_has_noncoherent_dma() sub-condition from the other half of the original commit b18d5431. Fixes: b18d5431 Cc: stable@vger.kernel.org Cc: Jordan Justen <jordan.l.justen@intel.com> Cc: Alex Williamson <alex.williamson@redhat.com> Reviewed-by: NXiao Guangrong <guangrong.xiao@linux.intel.com> Tested-by: NJanusz Mocek <januszmk6@gmail.com> Signed-off-by: Laszlo Ersek <lersek@redhat.com># Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
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