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54 lines
2.1 KiB
Diff
54 lines
2.1 KiB
Diff
From 879ae1880449c88db11c1ebdaedc2da79b2fe73f Mon Sep 17 00:00:00 2001
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From: Laszlo Ersek <lersek@redhat.com>
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Date: Wed, 4 Nov 2015 12:54:41 +0100
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Subject: KVM: x86: obey KVM_X86_QUIRK_CD_NW_CLEARED in kvm_set_cr0()
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Commit b18d5431acc7 ("KVM: x86: fix CR0.CD virtualization") was
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technically correct, but it broke OVMF guests by slowing down various
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parts of the firmware.
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Commit fb279950ba02 ("KVM: vmx: obey KVM_QUIRK_CD_NW_CLEARED") quirked the
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first function modified by b18d5431acc7, vmx_get_mt_mask(), for OVMF's
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sake. This restored the speed of the OVMF code that runs before
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PlatformPei (including the memory intensive LZMA decompression in SEC).
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This patch extends the quirk to the second function modified by
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b18d5431acc7, kvm_set_cr0(). It eliminates the intrusive slowdown that
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hits the EFI_MP_SERVICES_PROTOCOL implementation of edk2's
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UefiCpuPkg/CpuDxe -- which is built into OVMF --, when CpuDxe starts up
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all APs at once for initialization, in order to count them.
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We also carry over the kvm_arch_has_noncoherent_dma() sub-condition from
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the other half of the original commit b18d5431acc7.
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Fixes: b18d5431acc7a2fd22767925f3a6f597aa4bd29e
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Cc: stable@vger.kernel.org
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Cc: Jordan Justen <jordan.l.justen@intel.com>
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Cc: Alex Williamson <alex.williamson@redhat.com>
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Reviewed-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
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Tested-by: Janusz Mocek <januszmk6@gmail.com>
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Signed-off-by: Laszlo Ersek <lersek@redhat.com>#
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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---
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arch/x86/kvm/x86.c | 4 +++-
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1 file changed, 3 insertions(+), 1 deletion(-)
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diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
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index a24bae0..30723a4 100644
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--- a/arch/x86/kvm/x86.c
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+++ b/arch/x86/kvm/x86.c
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@@ -625,7 +625,9 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
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if ((cr0 ^ old_cr0) & update_bits)
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kvm_mmu_reset_context(vcpu);
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- if ((cr0 ^ old_cr0) & X86_CR0_CD)
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+ if (((cr0 ^ old_cr0) & X86_CR0_CD) &&
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+ kvm_arch_has_noncoherent_dma(vcpu->kvm) &&
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+ !kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED))
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kvm_zap_gfn_range(vcpu->kvm, 0, ~0ULL);
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return 0;
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--
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cgit v0.11.2
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