linux-kernel - Re: [PATCH] kvm: x86: fix x86 eflags fixed bit

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Date:	Wed, 08 Apr 2015 10:47:01 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Wanpeng Li <wanpeng.li@...ux.intel.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kvm: x86: fix x86 eflags fixed bit



On 08/04/2015 08:08, Wanpeng Li wrote:
> Guest can't be booted w/ ept=0, there is a message dumped as below:
> 
> If you're running a guest on an Intel machine without unrestricted mode
> support, the failure can be most likely due to the guest entering an invalid
> state for Intel VT. For example, the guest maybe running in big real mode
> which is not supported on less recent Intel processors.
> 
> EAX=00000011 EBX=f000d2f6 ECX=00006cac EDX=000f8956
> ESI=bffbdf62 EDI=00000000 EBP=00006c68 ESP=00006c68
> EIP=0000d187 EFL=00000004 [-----P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
> ES =e000 000e0000 ffffffff 00809300 DPL=0 DS16 [-WA]
> CS =f000 000f0000 ffffffff 00809b00 DPL=0 CS16 [-RA]
> SS =0000 00000000 ffffffff 00809300 DPL=0 DS16 [-WA]
> DS =0000 00000000 ffffffff 00809300 DPL=0 DS16 [-WA]
> FS =0000 00000000 ffffffff 00809300 DPL=0 DS16 [-WA]
> GS =0000 00000000 ffffffff 00809300 DPL=0 DS16 [-WA]
> LDT=0000 00000000 0000ffff 00008200 DPL=0 LDT
> TR =0000 00000000 0000ffff 00008b00 DPL=0 TSS32-busy
> GDT=     000f6a80 00000037
> IDT=     000f6abe 00000000
> CR0=00000011 CR2=00000000 CR3=00000000 CR4=00000000
> DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 
> DR6=00000000ffff0ff0 DR7=0000000000000400
> EFER=0000000000000000
> Code=01 1e b8 6a 2e 0f 01 16 74 6a 0f 20 c0 66 83 c8 01 0f 22 c0 <66> ea 8f d1 0f 00 08 00 b8 10 00 00 00 8e d8 8e c0 8e d0 8e e0 8e e8 89 c8 ff e2 89 c1 b8X
> 
> X86 eflags bit 1 is fixed set, which means that 1 << 1 is set instead of 1, 
> this patch fix it.
> 
> Signed-off-by: Wanpeng Li <wanpeng.li@...ux.intel.com>
> ---
>  arch/x86/kvm/emulate.c |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index b304728..630bcb0 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -2033,7 +2033,7 @@ static int emulate_iret_real(struct x86_emulate_ctxt *ctxt)
>  			     X86_EFLAGS_IF | X86_EFLAGS_DF | X86_EFLAGS_OF |
>  			     X86_EFLAGS_IOPL | X86_EFLAGS_NT | X86_EFLAGS_RF |
>  			     X86_EFLAGS_AC | X86_EFLAGS_ID |
> -			     X86_EFLAGS_FIXED_BIT;
> +			     X86_EFLAGS_FIXED;
>  	unsigned long vm86_mask = X86_EFLAGS_VM | X86_EFLAGS_VIF |
>  				  X86_EFLAGS_VIP;
>  
> @@ -2072,7 +2072,7 @@ static int emulate_iret_real(struct x86_emulate_ctxt *ctxt)
>  	}
>  
>  	ctxt->eflags &= ~EFLG_RESERVED_ZEROS_MASK; /* Clear reserved zeros */
> -	ctxt->eflags |= X86_EFLAGS_FIXED_BIT;
> +	ctxt->eflags |= X86_EFLAGS_FIXED;
>  	ctxt->ops->set_nmi_mask(ctxt, false);
>  
>  	return rc;
> @@ -2390,7 +2390,7 @@ static int em_syscall(struct x86_emulate_ctxt *ctxt)
>  
>  		ops->get_msr(ctxt, MSR_SYSCALL_MASK, &msr_data);
>  		ctxt->eflags &= ~msr_data;
> -		ctxt->eflags |= X86_EFLAGS_FIXED_BIT;
> +		ctxt->eflags |= X86_EFLAGS_FIXED;
>  #endif
>  	} else {
>  		/* legacy mode */
> 

Thanks Wanpeng.  Applied.

Paolo
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