powerpc/mm: Write to PTCR only if ultravisor disabled

In ultravisor enabled systems, PTCR becomes ultravisor privileged only
for writing and an attempt to write to it will cause a Hypervisor
Emulation Assitance interrupt.

This patch uses the set_ptcr_when_no_uv() function to restrict PTCR
writing to only when ultravisor is disabled.
Signed-off-by: Claudio Carvalho <cclaudio@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190822034838.27876-6-cclaudio@linux.ibm.com

arch/powerpc/include/asm/ultravisor.h

@@ -10,10 +10,22 @@
 
 #include <asm/asm-prototypes.h>
 #include <asm/ultravisor-api.h>
+#include <asm/firmware.h>
 
 int early_init_dt_scan_ultravisor(unsigned long node, const char *uname,
 				  int depth, void *data);
 
+/*
+ * In ultravisor enabled systems, PTCR becomes ultravisor privileged only for
+ * writing and an attempt to write to it will cause a Hypervisor Emulation
+ * Assistance interrupt.
+ */
+static inline void set_ptcr_when_no_uv(u64 val)
+{
+	if (!firmware_has_feature(FW_FEATURE_ULTRAVISOR))
+		mtspr(SPRN_PTCR, val);
+}
+
 static inline int uv_register_pate(u64 lpid, u64 dw0, u64 dw1)
 {
 	return ucall_norets(UV_WRITE_PATE, lpid, dw0, dw1);

arch/powerpc/mm/book3s64/hash_utils.c

@@ -61,6 +61,7 @@
 #include <asm/ps3.h>
 #include <asm/pte-walk.h>
 #include <asm/asm-prototypes.h>
+#include <asm/ultravisor.h>
 
 #include <mm/mmu_decl.h>
 
@@ -1075,8 +1076,8 @@ void hash__early_init_mmu_secondary(void)
 		if (!cpu_has_feature(CPU_FTR_ARCH_300))
 			mtspr(SPRN_SDR1, _SDR1);
 		else
-			mtspr(SPRN_PTCR,
-			      __pa(partition_tb) | (PATB_SIZE_SHIFT - 12));
+			set_ptcr_when_no_uv(__pa(partition_tb) |
+					    (PATB_SIZE_SHIFT - 12));
 	}
 	/* Initialize SLB */
 	slb_initialize();

arch/powerpc/mm/book3s64/pgtable.c

@@ -207,7 +207,7 @@ void __init mmu_partition_table_init(void)
 	 * 64 K size.
 	 */
 	ptcr = __pa(partition_tb) | (PATB_SIZE_SHIFT - 12);
-	mtspr(SPRN_PTCR, ptcr);
+	set_ptcr_when_no_uv(ptcr);
 	powernv_set_nmmu_ptcr(ptcr);
 }
 

arch/powerpc/mm/book3s64/radix_pgtable.c

@@ -27,6 +27,7 @@
 #include <asm/sections.h>
 #include <asm/trace.h>
 #include <asm/uaccess.h>
+#include <asm/ultravisor.h>
 
 #include <trace/events/thp.h>
 
@@ -650,8 +651,9 @@ void radix__early_init_mmu_secondary(void)
 		lpcr = mfspr(SPRN_LPCR);
 		mtspr(SPRN_LPCR, lpcr | LPCR_UPRT | LPCR_HR);
 
-		mtspr(SPRN_PTCR,
-		      __pa(partition_tb) | (PATB_SIZE_SHIFT - 12));
+		set_ptcr_when_no_uv(__pa(partition_tb) |
+				    (PATB_SIZE_SHIFT - 12));
+
 		radix_init_amor();
 	}
 
@@ -667,7 +669,7 @@ void radix__mmu_cleanup_all(void)
 	if (!firmware_has_feature(FW_FEATURE_LPAR)) {
 		lpcr = mfspr(SPRN_LPCR);
 		mtspr(SPRN_LPCR, lpcr & ~LPCR_UPRT);
-		mtspr(SPRN_PTCR, 0);
+		set_ptcr_when_no_uv(0);
 		powernv_set_nmmu_ptcr(0);
 		radix__flush_tlb_all();
 	}