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Re: [Qemu-devel] [PATCH] Correctly re-init EFER state during INIT IPI
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] Correctly re-init EFER state during INIT IPI |
Date: |
Thu, 1 Oct 2015 10:28:52 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 |
On 01/10/2015 00:33, Bill Paul wrote:
> When doing a re-initialization of a CPU core, the default state is to _not_
> have 64-bit long mode enabled. This means the LME (long mode enable) and LMA
> (long mode active) bits in the EFER model-specific register should be cleared.
>
> However, the EFER state is part of the CPU environment which is
> preserved by do_cpu_init(), so if EFER.LME and EFER.LMA were set at the
> time an INIT IPI was received, they will remain set after the init completes.
>
> This is contrary to what the Intel architecture manual describes and what
> happens on real hardware, and it leaves the CPU in a weird state that the
> guest can't clear.
>
> To fix this, the 'efer' member of the CPUX86State structure has been moved
> to an area outside the region preserved by do_cpu_init(), so that it can
> be properly re-initialized by x86_cpu_reset().
>
> Signed-off-by: Bill Paul <address@hidden>
> CC: Paolo Bonzini <address@hidden>
> CC: Richard Henderson <address@hidden>
> CC: Eduardo Habkost <address@hidden>
Reviewed-by: Paolo Bonzini <address@hidden>
> ---
> target-i386/cpu.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index 034fab6..fac773c 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -833,6 +833,7 @@ typedef struct CPUX86State {
> BNDReg bnd_regs[4];
> BNDCSReg bndcs_regs;
> uint64_t msr_bndcfgs;
> + uint64_t efer;
>
> /* Beginning of state preserved by INIT (dummy marker). */
> struct {} start_init_save;
> @@ -865,7 +866,6 @@ typedef struct CPUX86State {
> uint32_t sysenter_cs;
> target_ulong sysenter_esp;
> target_ulong sysenter_eip;
> - uint64_t efer;
> uint64_t star;
>
> uint64_t vm_hsave;
>