From 4edaac512c8a31b0aa715b58ee00ee06df642fa2 Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu Date: Mon, 19 Aug 2019 23:13:22 -0300 Subject: [PATCH] powerpc/pseries/svm: Disable doorbells in SVM guests Normally, the HV emulates some instructions like MSGSNDP, MSGCLRP from a KVM guest. To emulate the instructions, it must first read the instruction from the guest's memory and decode its parameters. However for a secure guest (aka SVM), the page containing the instruction is in secure memory and the HV cannot access directly. It would need the Ultravisor (UV) to facilitate accessing the instruction and parameters but the UV currently does not have the support for such accesses. Until the UV has such support, disable doorbells in SVMs. This might incur a performance hit but that is yet to be quantified. With this patch applied (needed only in SVMs not needed for HV) we are able to launch SVM guests with multi-core support. Eg: qemu -smp sockets=2,cores=2,threads=2. Fix suggested by Benjamin Herrenschmidt. Thanks to input from Paul Mackerras, Ram Pai and Michael Anderson. Signed-off-by: Sukadev Bhattiprolu Signed-off-by: Thiago Jung Bauermann Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190820021326.6884-13-bauerman@linux.ibm.com --- arch/powerpc/platforms/pseries/smp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/platforms/pseries/smp.c b/arch/powerpc/platforms/pseries/smp.c index 4b3ef8d9c63f..ad61e90032da 100644 --- a/arch/powerpc/platforms/pseries/smp.c +++ b/arch/powerpc/platforms/pseries/smp.c @@ -41,6 +41,7 @@ #include #include #include +#include #include "pseries.h" #include "offline_states.h" @@ -221,7 +222,7 @@ static __init void pSeries_smp_probe_xics(void) { xics_smp_probe(); - if (cpu_has_feature(CPU_FTR_DBELL)) + if (cpu_has_feature(CPU_FTR_DBELL) && !is_secure_guest()) smp_ops->cause_ipi = smp_pseries_cause_ipi; else smp_ops->cause_ipi = icp_ops->cause_ipi; -- 2.20.1