On 06.12.2022 14:53, Jan Beulich wrote:
> While plausible to do what was intended based on the name of the flag
> (PGC_page_table), that name was misleading and is going to be changed.
> It marks page tables pages _having_ a shadow, not shadows of page table
> pages. The attempt also didn't cover the HAP case at all, and it
> constituted a potentially very long loop doing nothing when
> !SHADOW_PAGING. Instead leave a comment of what actually wants doing
> there (which then also may need to account for e.g. the risk of A/D bits
> becoming set behind our backs).
>
> Signed-off-by: Jan Beulich <[email protected]>
I'm sorry, I should have Cc-ed tboot reviewers here as well.
Jan
> --- a/xen/arch/x86/tboot.c
> +++ b/xen/arch/x86/tboot.c
> @@ -177,29 +177,6 @@ static void update_iommu_mac(vmac_ctx_t
> #define is_page_in_use(page) \
> (page_state_is(page, inuse) || page_state_is(page, offlining))
>
> -static void update_pagetable_mac(vmac_ctx_t *ctx)
> -{
> - unsigned long mfn;
> -
> - for ( mfn = 0; mfn < max_page; mfn++ )
> - {
> - struct page_info *page = mfn_to_page(_mfn(mfn));
> -
> - if ( !mfn_valid(_mfn(mfn)) )
> - continue;
> - if ( is_page_in_use(page) && !is_special_page(page) )
> - {
> - if ( page->count_info & PGC_page_table )
> - {
> - void *pg = map_domain_page(_mfn(mfn));
> -
> - vmac_update(pg, PAGE_SIZE, ctx);
> - unmap_domain_page(pg);
> - }
> - }
> - }
> -}
> -
> static void tboot_gen_domain_integrity(const uint8_t key[TB_KEY_SIZE],
> vmac_t *mac)
> {
> @@ -233,8 +210,7 @@ static void tboot_gen_domain_integrity(c
> }
> }
>
> - /* MAC all shadow page tables */
> - update_pagetable_mac(&ctx);
> + /* TODO: MAC all shadow / HAP page tables */
>
> *mac = vmac(NULL, 0, nonce, NULL, &ctx);
>
>
>
