Commit 512a5a64 authored Aug 22, 2019 by Claudio Carvalho Committed by Michael Ellerman Aug 30, 2019

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 <cclaudio@linux.ibm.com>
Reviewed-by: Ram Pai <linuxram@us.ibm.com>
Reviewed-by: Ryan Grimm <grimm@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190822034838.27876-7-cclaudio@linux.ibm.com

parent 52231340

arch/powerpc/platforms/powernv/idle.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -675,6 +675,7 @@ 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);
		if (!firmware_has_feature(FW_FEATURE_ULTRAVISOR))
		sprs.ldbar = mfspr(SPRN_LDBAR);

		sprs_saved = true;
		@@ -789,6 +790,7 @@ core_woken:
		mtspr(SPRN_MMCR0, sprs.mmcr0);
		mtspr(SPRN_MMCR1, sprs.mmcr1);
		mtspr(SPRN_MMCR2, sprs.mmcr2);
		if (!firmware_has_feature(FW_FEATURE_ULTRAVISOR))
		mtspr(SPRN_LDBAR, sprs.ldbar);

		mtspr(SPRN_SPRG3, local_paca->sprg_vdso);

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