2016-04-22 12:56-0600, Bruce Rogers:
> Commit d28bc9dd25ce reversed the order of two lines which initialize cr0,
> allowing the current (old) cr0 value to mess up vcpu initialization.
> This was observed in the checks for cr0 X86_CR0_WP bit in the context of
> kvm_mmu_reset_context(). Besides, setting vcpu->arch.cr0 after vmx_set_cr0()
> is completely redundant. Change the order back to ensure proper vcpu
> initialization.
>
> The combination of booting with ovmf firmware when guest vcpus > 1 and kvm's
> ept=N option being set results in a VM-entry failure. This patch fixes that.
Greg pointed out missing,
Cc: stable@xxxxxxxxxxxxxxx
when stable@xxxxxxxxxxxxxxx was Cc'd. Adding
Fixes: d28bc9dd25ce ("KVM: x86: INIT and reset sequences are different")
would be nice too (even when it is redundant).
> Signed-off-by: Bruce Rogers <brogers@xxxxxxxx>
> ---
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> @@ -5046,8 +5046,8 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
> cr0 = X86_CR0_NW | X86_CR0_CD | X86_CR0_ET;
> - vmx_set_cr0(vcpu, cr0); /* enter rmode */
> vmx->vcpu.arch.cr0 = cr0;
> + vmx_set_cr0(vcpu, cr0); /* enter rmode */
So vmx_set_cr0() has a code that depends on vmx->vcpu.arch.cr0 being
already set the to new value. Do you know what function is it?
I think we better set vmx->vcpu.arch.cr0 early in vmx_set_cr0().
Or do other callsites somehow depend on the old cr0 value?
Thanks.
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