From 24d5282527f4647907b3572820b5335c15cd0356 Mon Sep 17 00:00:00 2001 From: Razvan Cojocaru Date: Mon, 18 Feb 2019 13:46:02 +0100 Subject: [PATCH] x86/altp2m: fix HVMOP_altp2m_set_domain_state race HVMOP_altp2m_set_domain_state does not domain_pause(), presumably on purpose (as it was originally supposed to cater to a in-guest agent, and a domain pausing itself is not a good idea). This can lead to domain crashes in the vmx_vmexit_handler() code that checks if the guest has the ability to switch EPTP without an exit. That code can __vmread() the host p2m's EPT_POINTER (before HVMOP_altp2m_set_domain_state "for_each_vcpu()" has a chance to run altp2m_vcpu_initialise(), but after d->arch.altp2m_active is set). Signed-off-by: Razvan Cojocaru Acked-by: Jan Beulich Release-acked-by: Juergen Gross --- xen/arch/x86/hvm/hvm.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c index 410623d437..79c7d816e2 100644 --- a/xen/arch/x86/hvm/hvm.c +++ b/xen/arch/x86/hvm/hvm.c @@ -4538,6 +4538,10 @@ static int do_altp2m_op( break; } + rc = domain_pause_except_self(d); + if ( rc ) + break; + ostate = d->arch.altp2m_active; d->arch.altp2m_active = !!a.u.domain_state.state; @@ -4556,6 +4560,8 @@ static int do_altp2m_op( if ( ostate ) p2m_flush_altp2m(d); } + + domain_unpause_except_self(d); break; } -- 2.30.2