From 512a5a6452b6d742b6f713184414d28cb6413080 Mon Sep 17 00:00:00 2001 From: Claudio Carvalho Date: Thu, 22 Aug 2019 00:48:37 -0300 Subject: [PATCH] powerpc/powernv: Access LDBAR only if ultravisor disabled LDBAR is a per-thread SPR populated and used by the thread-imc pmu driver to dump the data counter into memory. It contains memory along with few other configuration bits. LDBAR is populated and enabled only when any of the thread imc pmu events are monitored. In ultravisor enabled systems, LDBAR becomes ultravisor privileged and an attempt to write to it will cause a Hypervisor Emulation Assistance interrupt. In ultravisor enabled systems, the ultravisor is responsible to maintain the LDBAR (e.g. save and restore it). This restricts LDBAR access to only when ultravisor is disabled. Signed-off-by: Claudio Carvalho Reviewed-by: Ram Pai Reviewed-by: Ryan Grimm Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20190822034838.27876-7-cclaudio@linux.ibm.com --- arch/powerpc/platforms/powernv/idle.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c index 09f49ee..78599bc 100644 --- a/arch/powerpc/platforms/powernv/idle.c +++ b/arch/powerpc/platforms/powernv/idle.c @@ -675,7 +675,8 @@ static unsigned long power9_idle_stop(unsigned long psscr, bool mmu_on) sprs.ptcr = mfspr(SPRN_PTCR); sprs.rpr = mfspr(SPRN_RPR); sprs.tscr = mfspr(SPRN_TSCR); - sprs.ldbar = mfspr(SPRN_LDBAR); + if (!firmware_has_feature(FW_FEATURE_ULTRAVISOR)) + sprs.ldbar = mfspr(SPRN_LDBAR); sprs_saved = true; @@ -789,7 +790,8 @@ core_woken: mtspr(SPRN_MMCR0, sprs.mmcr0); mtspr(SPRN_MMCR1, sprs.mmcr1); mtspr(SPRN_MMCR2, sprs.mmcr2); - mtspr(SPRN_LDBAR, sprs.ldbar); + if (!firmware_has_feature(FW_FEATURE_ULTRAVISOR)) + mtspr(SPRN_LDBAR, sprs.ldbar); mtspr(SPRN_SPRG3, local_paca->sprg_vdso); -- 2.7.4