linux-kernel - Re: [PATCH v2 2/2] KVM: x86/mmu: Derive EPT violation RWX bits from EPTE RWX bits

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Message-ID: <20220408211140.GE857847@ls.amr.corp.intel.com>
Date:   Fri, 8 Apr 2022 14:11:40 -0700
From:   Isaku Yamahata <isaku.yamahata@...il.com>
To:     SU Hang <darcy.sh@...group.com>
Cc:     seanjc@...gle.com, kvm@...r.kernel.org,
        Lai Jiangshan <jiangshan.ljs@...group.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Kr???m?????? <rkrcmar@...hat.com>,
        linux-kernel@...r.kernel.org, isaku.yamahata@...il.com
Subject: Re: [PATCH v2 2/2] KVM: x86/mmu: Derive EPT violation RWX bits from
 EPTE RWX bits

On Tue, Mar 29, 2022 at 11:01:07AM +0800,
SU Hang <darcy.sh@...group.com> wrote:

> From: Sean Christopherson <seanjc@...gle.com>
> 
> Derive the mask of RWX bits reported on EPT violations from the mask of
> RWX bits that are shoved into EPT entries; the layout is the same, the
> EPT violation bits are simply shifted by three.  Use the new shift and a
> slight copy-paste of the mask derivation instead of completely open
> coding the same to convert between the EPT entry bits and the exit
> qualification when synthesizing a nested EPT Violation.
> 
> No functional change intended.
> 
> Cc: SU Hang <darcy.sh@...group.com>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> ---
>  arch/x86/include/asm/vmx.h     | 7 +------
>  arch/x86/kvm/mmu/paging_tmpl.h | 8 +++++++-
>  arch/x86/kvm/vmx/vmx.c         | 4 +---
>  3 files changed, 9 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
> index 3586d4aeaac7..46bc7072f6a2 100644
> --- a/arch/x86/include/asm/vmx.h
> +++ b/arch/x86/include/asm/vmx.h
> @@ -543,17 +543,12 @@ enum vm_entry_failure_code {
>  #define EPT_VIOLATION_ACC_READ_BIT	0
>  #define EPT_VIOLATION_ACC_WRITE_BIT	1
>  #define EPT_VIOLATION_ACC_INSTR_BIT	2
> -#define EPT_VIOLATION_READABLE_BIT	3
> -#define EPT_VIOLATION_WRITABLE_BIT	4
> -#define EPT_VIOLATION_EXECUTABLE_BIT	5
>  #define EPT_VIOLATION_GVA_IS_VALID_BIT	7
>  #define EPT_VIOLATION_GVA_TRANSLATED_BIT 8
>  #define EPT_VIOLATION_ACC_READ		(1 << EPT_VIOLATION_ACC_READ_BIT)
>  #define EPT_VIOLATION_ACC_WRITE		(1 << EPT_VIOLATION_ACC_WRITE_BIT)
>  #define EPT_VIOLATION_ACC_INSTR		(1 << EPT_VIOLATION_ACC_INSTR_BIT)
> -#define EPT_VIOLATION_READABLE		(1 << EPT_VIOLATION_READABLE_BIT)
> -#define EPT_VIOLATION_WRITABLE		(1 << EPT_VIOLATION_WRITABLE_BIT)
> -#define EPT_VIOLATION_EXECUTABLE	(1 << EPT_VIOLATION_EXECUTABLE_BIT)
> +#define EPT_VIOLATION_RWX_MASK		(VMX_EPT_RWX_MASK << EPT_VIOLATION_RWX_SHIFT)


"#define EPT_VIOLATION_RWX_SHIFT 3" is missing.
It fails to compile.

  CC [M]  arch/x86/kvm/vmx/vmx.o
In file included from linux/arch/x86/include/asm/virtext.h:18,
                 from /linux/arch/x86/kvm/vmx/vmx.c:49:
/linux/arch/x86/kvm/vmx/vmx.c: In function 'handle_ept_violation':
/linux/arch/x86/include/asm/vmx.h:551:54: error: 'EPT_VIOLATION_RWX_SHIFT' undeclared (first use in this function); did you mean 'EPT_VIOLATION_RWX_MASK'?
  551 | #define EPT_VIOLATION_RWX_MASK  (VMX_EPT_RWX_MASK << EPT_VIOLATION_RWX_SHIFT)
      |                                                      ^~~~~~~~~~~~~~~~~~~~~~~

Thanks,
-- 
Isaku Yamahata <isaku.yamahata@...il.com>