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Re: [Qemu-devel] [PATCH 1/3] target-i386: fix segment flags for SMM, use
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 1/3] target-i386: fix segment flags for SMM, user-mode emulation and VM86 mode |
Date: |
Wed, 28 May 2014 13:34:16 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 |
Il 27/05/2014 22:33, Bandan Das ha scritto:
> With the next patch, these need to be correct or VM86 tasks
> have the wrong CPL. The flags are basically what the Intel VMX
> documentation say is mandatory for entry into a VM86 guest.
Are you referring to 26.3.1.2 ?
Yes:
CS, SS, DS, ES, FS, GS.
If the guest will be virtual-8086, the field must be 000000F3H. This
implies the following:
- Bits 3:0 (Type) must be 3, indicating an expand-up read/write accessed
data segment.
- Bit 4 (S) must be 1.
- Bits 6:5 (DPL) must be 3.
- Bit 7 (P) must be 1.
- Bits 11:8 (reserved), bit 12 (software available), bit 13
(reserved/L), bit 14 (D/B), bit 15 (G), bit 16 (unusable), and bits
31:17 (reserved) must all be 0.
Paolo
Just a nit, I guess it helps
to add a pointer in the comments for someone (like me :)) going
through the code.
- [Qemu-devel] [PATCH 3/3] target-i386: get CPL from SS.DPL, (continued)
Re: [Qemu-devel] [PATCH 3/3] target-i386: get CPL from SS.DPL, Bandan Das, 2014/05/27
[Qemu-devel] [PATCH 1/3] target-i386: fix segment flags for SMM, user-mode emulation and VM86 mode, Paolo Bonzini, 2014/05/16
[Qemu-devel] [PATCH 2/3] target-i386: rework CPL checks during task switch, preparing for next patch, Paolo Bonzini, 2014/05/16