RMRRs are setup ahead of populating the p2m and hence the ASSERT when populating the low 1MB needs to be relaxed when it finds an existing entry: it's either RAM or a RMRR resulting from the IOMMU setup.
Rework the logic a bit and introduce a local mfn variable in order to assert that if the gfn is populated and not RAM it is an identity map. Fixes: 6b4f6a31ac ('x86/PVH: de-duplicate mappings for first Mb of Dom0 memory') Signed-off-by: Roger Pau Monné <roger....@citrix.com> Reviewed-by: Jan Beulich <jbeul...@suse.com> --- Changes since v1: - Fix indentation. - Expand existing assert. --- xen/arch/x86/hvm/dom0_build.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/xen/arch/x86/hvm/dom0_build.c b/xen/arch/x86/hvm/dom0_build.c index b00e45885c..63dceb2116 100644 --- a/xen/arch/x86/hvm/dom0_build.c +++ b/xen/arch/x86/hvm/dom0_build.c @@ -466,11 +466,16 @@ static int __init pvh_populate_p2m(struct domain *d) for ( i = rc = 0; i < MB1_PAGES; ++i ) { p2m_type_t p2mt; + mfn_t mfn = get_gfn_query(d, i, &p2mt); - if ( mfn_eq(get_gfn_query(d, i, &p2mt), INVALID_MFN) ) + if ( mfn_eq(mfn, INVALID_MFN) ) rc = set_mmio_p2m_entry(d, _gfn(i), _mfn(i), PAGE_ORDER_4K); else - ASSERT(p2mt == p2m_ram_rw); + /* + * If the p2m entry is already set it must belong to a RMRR and + * already be identity mapped, or be a RAM region. + */ + ASSERT(p2mt == p2m_ram_rw || mfn_eq(mfn, _mfn(i))); put_gfn(d, i); if ( rc ) { -- 2.34.1