From f61c54967f4a5ea7e0c9fc3a4e966efa26481cb9 Mon Sep 17 00:00:00 2001 From: Andrew Cooper Date: Tue, 19 Jul 2022 21:37:43 +0100 Subject: [PATCH] x86/pv: Inject #GP for implicit grant unmaps This is a debug behaviour to identify buggy kernels. Crashing the domain is the most unhelpful thing to do, because it discards the relevant context. Instead, inject #GP[0] like other permission errors in x86. In particular, this lets the kernel provide a backtrace which is more likely to be helpful to a developer. As a bugfix, this always injects #GP[0] to current, not l1e_owner. It is not l1e_owner's fault if dom0 using superpowers triggers an implicit unmap. Signed-off-by: Andrew Cooper Acked-by: Jan Beulich --- xen/arch/x86/mm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c index 2c1c35151a..22a4dfa838 100644 --- a/xen/arch/x86/mm.c +++ b/xen/arch/x86/mm.c @@ -1229,10 +1229,10 @@ void put_page_from_l1e(l1_pgentry_t l1e, struct domain *l1e_owner) if ( (l1e_get_flags(l1e) & _PAGE_GNTTAB) && !l1e_owner->is_shutting_down && !l1e_owner->is_dying ) { - gdprintk(XENLOG_WARNING, - "Attempt to implicitly unmap a granted PTE %" PRIpte "\n", - l1e_get_intpte(l1e)); - domain_crash(l1e_owner); + gprintk(XENLOG_WARNING, + "Attempt to implicitly unmap %pd's grant PTE %" PRIpte "\n", + l1e_owner, l1e_get_intpte(l1e)); + pv_inject_hw_exception(TRAP_gp_fault, 0); } #endif -- 2.30.2