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SubjectRe: [PATCH v2 2/2] KVM: x86/mmu: Derive EPT violation RWX bits from EPTE RWX bits
On Fri, Apr 08, 2022, Isaku Yamahata wrote:
> On Tue, Mar 29, 2022 at 11:01:07AM +0800,
> SU Hang <darcy.sh@antgroup.com> wrote:
>
> > From: Sean Christopherson <seanjc@google.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@antgroup.com>
> > Signed-off-by: Sean Christopherson <seanjc@google.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)
> | ^~~~~~~~~~~~~~~~~~~~~~~

Yeah, not sure how that one line got dropped.

https://lore.kernel.org/all/20220408202815.386932-1-seanjc@google.com

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