forked from SLFO-pool/xen
73 lines
2.7 KiB
Diff
73 lines
2.7 KiB
Diff
# Commit 777c71d31325bc55ba1cc3f317d4155fe519ab0b
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# Date 2024-06-13 16:54:17 +0200
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# Author Jan Beulich <jbeulich@suse.com>
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# Committer Jan Beulich <jbeulich@suse.com>
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x86/EPT: avoid marking non-present entries for re-configuring
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For non-present entries EMT, like most other fields, is meaningless to
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hardware. Make the logic in ept_set_entry() setting the field (and iPAT)
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conditional upon dealing with a present entry, leaving the value at 0
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otherwise. This has two effects for epte_get_entry_emt() which we'll
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want to leverage subsequently:
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1) The call moved here now won't be issued with INVALID_MFN anymore (a
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respective BUG_ON() is being added).
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2) Neither of the other two calls could now be issued with a truncated
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form of INVALID_MFN anymore (as long as there's no bug anywhere
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marking an entry present when that was populated using INVALID_MFN).
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Signed-off-by: Jan Beulich <jbeulich@suse.com>
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Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
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--- a/xen/arch/x86/mm/p2m-ept.c
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+++ b/xen/arch/x86/mm/p2m-ept.c
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@@ -649,6 +649,8 @@ static int cf_check resolve_misconfig(st
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if ( e.emt != MTRR_NUM_TYPES )
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break;
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+ ASSERT(is_epte_present(&e));
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+
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if ( level == 0 )
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{
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for ( gfn -= i, i = 0; i < EPT_PAGETABLE_ENTRIES; ++i )
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@@ -914,17 +916,6 @@ ept_set_entry(struct p2m_domain *p2m, gf
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if ( mfn_valid(mfn) || p2m_allows_invalid_mfn(p2mt) )
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{
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- bool ipat;
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- int emt = epte_get_entry_emt(p2m->domain, _gfn(gfn), mfn,
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- i * EPT_TABLE_ORDER, &ipat,
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- p2mt);
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-
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- if ( emt >= 0 )
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- new_entry.emt = emt;
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- else /* ept_handle_misconfig() will need to take care of this. */
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- new_entry.emt = MTRR_NUM_TYPES;
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-
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- new_entry.ipat = ipat;
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new_entry.sp = !!i;
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new_entry.sa_p2mt = p2mt;
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new_entry.access = p2ma;
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@@ -940,6 +931,22 @@ ept_set_entry(struct p2m_domain *p2m, gf
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need_modify_vtd_table = 0;
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ept_p2m_type_to_flags(p2m, &new_entry);
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+
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+ if ( is_epte_present(&new_entry) )
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+ {
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+ bool ipat;
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+ int emt = epte_get_entry_emt(p2m->domain, _gfn(gfn), mfn,
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+ i * EPT_TABLE_ORDER, &ipat,
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+ p2mt);
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+
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+ BUG_ON(mfn_eq(mfn, INVALID_MFN));
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+
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+ if ( emt >= 0 )
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+ new_entry.emt = emt;
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+ else /* ept_handle_misconfig() will need to take care of this. */
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+ new_entry.emt = MTRR_NUM_TYPES;
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+ new_entry.ipat = ipat;
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+ }
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}
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if ( sve != -1 )
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