arm64/boot: Disable trapping of PMZR_EL0 writes to EL2grafted

__init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2.
PMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in
HDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host
traps to EL2, where the nVHE hypervisor has no handler and BUG()s. The
kernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU
driver set PMUSERENR_EL0.UEN for a task with a user-read event, so a
write from EL0 reaches the trap and takes the host down without a panic
message.

Accumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already
does for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9
bits.

Fixes: 858c7bfcb35e1 ("arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9")
Cc: stable@vger.kernel.org
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oliver Upton <oupton@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>

1 files changed, 40 insertions, 0 deletions

diff --git a/include/xen/balloon.h b/include/xen/balloon.h
new file mode 100644
index 000000000..f78a6cc94
--- /dev/null
+++ b/include/xen/balloon.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/******************************************************************************
+ * Xen balloon functionality
+ */
+#ifndef _XEN_BALLOON_H
+#define _XEN_BALLOON_H
+
+#define RETRY_UNLIMITED	0
+
+struct balloon_stats {
+	/* We aim for 'current allocation' == 'target allocation'. */
+	unsigned long current_pages;
+	unsigned long target_pages;
+	unsigned long target_unpopulated;
+	/* Number of pages in high- and low-memory balloons. */
+	unsigned long balloon_low;
+	unsigned long balloon_high;
+	unsigned long total_pages;
+	unsigned long schedule_delay;
+	unsigned long max_schedule_delay;
+	unsigned long retry_count;
+	unsigned long max_retry_count;
+};
+
+extern struct balloon_stats balloon_stats;
+
+void balloon_set_new_target(unsigned long target);
+
+int xen_alloc_ballooned_pages(unsigned int nr_pages, struct page **pages);
+void xen_free_ballooned_pages(unsigned int nr_pages, struct page **pages);
+
+#ifdef CONFIG_XEN_BALLOON
+void xen_balloon_init(void);
+#else
+static inline void xen_balloon_init(void)
+{
+}
+#endif
+
+#endif	/* _XEN_BALLOON_H */