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Date: Sat, 9 Jul 2022 11:26:26 +0700
From: Bagas Sanjaya <bagasdotme@...il.com>
To: linux-doc@...r.kernel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>,
Jonathan Corbet <corbet@....net>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"H. Peter Anvin" <hpa@...or.com>,
Isaku Yamahata <isaku.yamahata@...el.com>,
Kai Huang <kai.huang@...el.com>, x86@...nel.org,
kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 08/12] Documentation: kvm: tdx-tdp-mmu: Properly format
nested list for EPT state machine
On Sat, Jul 09, 2022 at 11:20:34AM +0700, Bagas Sanjaya wrote:
> The state machine of EPT entry
> ------------------------------
> -(private EPT entry, shared EPT entry) =
> - (non-present, non-present): private mapping is allowed
> - (present, non-present): private mapping is mapped
> - (non-present | SPTE_SHARED_MASK, non-present | SPTE_SHARED_MASK):
> - shared mapping is allowed
> - (non-present | SPTE_SHARED_MASK, present | SPTE_SHARED_MASK):
> - shared mapping is mapped
> - (present | SPTE_SHARED_MASK, any) invalid combination
> +* (private EPT entry, shared EPT entry)
>
> -* map_gpa(private GPA): Mark the region that private GPA is allowed(NEW)
> - private EPT entry: clear SPTE_SHARED_MASK
> - present: nop
> - non-present: nop
> - non-present | SPTE_SHARED_MASK -> non-present (clear SPTE_SHARED_MASK)
> + * (non-present, non-present):
> + private mapping is allowed
> + * (present, non-present):
> + private mapping is mapped
> + * (non-present | SPTE_SHARED_MASK, non-present | SPTE_SHARED_MASK):
> + shared mapping is allowed
> + * (non-present | SPTE_SHARED_MASK, present | SPTE_SHARED_MASK):
> + shared mapping is mapped
> + * (present | SPTE_SHARED_MASK, any):
> + invalid combination
>
> - shared EPT entry: zap the entry, clear SPTE_SHARED_MASK
> - present: invalid
> - non-present -> non-present: nop
> - present | SPTE_SHARED_MASK -> non-present
> - non-present | SPTE_SHARED_MASK -> non-present
> +* map_gpa (private GPA): Mark the region that private GPA is allowed(NEW)
>
> -* map_gpa(shared GPA): Mark the region that shared GPA is allowed(NEW)
> - private EPT entry: zap and set SPTE_SHARED_MASK
> - present -> non-present | SPTE_SHARED_MASK
> - non-present -> non-present | SPTE_SHARED_MASK
> - non-present | SPTE_SHARED_MASK: nop
> + * private EPT entry: clear SPTE_SHARED_MASK
>
> - shared EPT entry: set SPTE_SHARED_MASK
> - present: invalid
> - non-present -> non-present | SPTE_SHARED_MASK
> - present | SPTE_SHARED_MASK -> present | SPTE_SHARED_MASK: nop
> - non-present | SPTE_SHARED_MASK -> non-present | SPTE_SHARED_MASK: nop
> + * present: nop
> + * non-present: nop
> + * non-present | SPTE_SHARED_MASK -> non-present (clear SPTE_SHARED_MASK)
>
> -* map(private GPA)
> - private EPT entry
> - present: nop
> - non-present -> present
> - non-present | SPTE_SHARED_MASK: nop. looping on EPT violation(NEW)
> + * shared EPT entry: zap the entry, clear SPTE_SHARED_MASK
>
> - shared EPT entry: nop
> + * present: invalid
> + * non-present -> non-present: nop
> + * present | SPTE_SHARED_MASK -> non-present
> + * non-present | SPTE_SHARED_MASK -> non-present
>
> -* map(shared GPA)
> - private EPT entry: nop
> +* map_gpa (shared GPA): Mark the region that shared GPA is allowed(NEW)
>
> - shared EPT entry
> - present: invalid
> - present | SPTE_SHARED_MASK: nop
> - non-present | SPTE_SHARED_MASK -> present | SPTE_SHARED_MASK
> - non-present: nop. looping on EPT violation(NEW)
> + * private EPT entry: zap and set SPTE_SHARED_MASK
>
> -* zap(private GPA)
> - private EPT entry: zap the entry with keeping SPTE_SHARED_MASK
> - present -> non-present
> - present | SPTE_SHARED_MASK: invalid
> - non-present: nop as is_shadow_present_pte() is checked
> - non-present | SPTE_SHARED_MASK: nop as is_shadow_present_pte() is
> - checked
> + * present -> non-present | SPTE_SHARED_MASK
> + * non-present -> non-present | SPTE_SHARED_MASK
> + * non-present | SPTE_SHARED_MASK: nop
>
> - shared EPT entry: nop
> + * shared EPT entry: set SPTE_SHARED_MASK
>
> -* zap(shared GPA)
> - private EPT entry: nop
> + * present: invalid
> + * non-present -> non-present | SPTE_SHARED_MASK
> + * present | SPTE_SHARED_MASK -> present | SPTE_SHARED_MASK: nop
> + * non-present | SPTE_SHARED_MASK -> non-present | SPTE_SHARED_MASK: nop
>
> - shared EPT entry: zap
> - any -> non-present
> - present: invalid
> - present | SPTE_SHARED_MASK -> non-present | SPTE_SHARED_MASK
> - non-present: nop as is_shadow_present_pte() is checked
> - non-present | SPTE_SHARED_MASK: nop as is_shadow_present_pte() is
> - checked
> +* map (private GPA)
> +
> + * private EPT entry
> +
> + * present: nop
> + * non-present -> present
> + * non-present | SPTE_SHARED_MASK: nop. looping on EPT violation(NEW)
> +
> + * shared EPT entry: nop
> +
> +* map (shared GPA)
> +
> + * private EPT entry: nop
> +
> + * shared EPT entry:
> +
> + * present: invalid
> + * present | SPTE_SHARED_MASK: nop
> + * non-present | SPTE_SHARED_MASK -> present | SPTE_SHARED_MASK
> + * non-present: nop. looping on EPT violation(NEW)
> +
> +* zap (private GPA)
> +
> + * private EPT entry: zap the entry with keeping SPTE_SHARED_MASK
> +
> + * present -> non-present
> + * present | SPTE_SHARED_MASK: invalid
> + * non-present: nop as is_shadow_present_pte() is checked
> + * non-present | SPTE_SHARED_MASK: nop as is_shadow_present_pte() is
> + checked
> +
> + * shared EPT entry: nop
> +
> +* zap (shared GPA)
> +
> + * private EPT entry: nop
> +
> + * shared EPT entry: zap
> +
> + * any -> non-present
> + * present: invalid
> + * present | SPTE_SHARED_MASK -> non-present | SPTE_SHARED_MASK
> + * non-present: nop as is_shadow_present_pte() is checked
> + * non-present | SPTE_SHARED_MASK: nop as is_shadow_present_pte() is
> + checked
IMO, the state machine lists above should have used tables instead.
--
An old man doll... just what I always wanted! - Clara
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