Mailing List Archive

commit f00ad745cfa774a269b28e88951b56b7001d4fe0
Author: Jan Beulich <jbeulich@suse.com>
AuthorDate: Mon Dec 12 12:17:07 2022 +0100
Commit: Jan Beulich <jbeulich@suse.com>
CommitDate: Mon Dec 12 12:17:07 2022 +0100

x86/tboot: drop failed attempt to hash shadow page tables

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 <jbeulich@suse.com>
Reviewed-by: Jason Andryuk <jandryuk@gmail.com>
---
xen/arch/x86/tboot.c | 26 +-------------------------
1 file changed, 1 insertion(+), 25 deletions(-)

diff --git a/xen/arch/x86/tboot.c b/xen/arch/x86/tboot.c
index 03098450f7..569732cffe 100644
--- a/xen/arch/x86/tboot.c
+++ b/xen/arch/x86/tboot.c
@@ -177,29 +177,6 @@ static void update_iommu_mac(vmac_ctx_t *ctx, uint64_t pt_maddr, int level)
#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(const uint8_t key[TB_KEY_SIZE],
}
}

- /* MAC all shadow page tables */
- update_pagetable_mac(&ctx);
+ /* TODO: MAC all shadow / HAP page tables */

*mac = vmac(NULL, 0, nonce, NULL, &ctx);

--
generated by git-patchbot for /home/xen/git/xen.git#master