powerpc fixes for 5.8 #7

A fix to the VAS code we merged this cycle, to report the proper error code to
 userspace for address translation failures. And a selftest update to match.
 
 Another fix for our pkey handling of PROT_EXEC mappings.
 
 A fix for a crash when booting a "secure VM" under an ultravisor with certain
 numbers of CPUs.
 
 Thanks to:
   Aneesh Kumar K.V, Haren Myneni, Laurent Dufour, Sandipan Das, Satheesh
   Rajendran, Thiago Jung Bauermann.
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Merge tag 'powerpc-5.8-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux into master

Pull powerpc fixes from Michael Ellerman:
 "Some more powerpc fixes for 5.8:

   - A fix to the VAS code we merged this cycle, to report the proper
     error code to userspace for address translation failures. And a
     selftest update to match.

   - Another fix for our pkey handling of PROT_EXEC mappings.

   - A fix for a crash when booting a "secure VM" under an ultravisor
     with certain numbers of CPUs.

  Thanks to: Aneesh Kumar K.V, Haren Myneni, Laurent Dufour, Sandipan
  Das, Satheesh Rajendran, Thiago Jung Bauermann"

* tag 'powerpc-5.8-7' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  selftests/powerpc: Use proper error code to check fault address
  powerpc/vas: Report proper error code for address translation failure
  powerpc/pseries/svm: Fix incorrect check for shared_lppaca_size
  powerpc/book3s64/pkeys: Fix pkey_access_permitted() for execute disable pkey

Documentation/powerpc/vas-api.rst

@@ -213,7 +213,7 @@ request buffers are not in memory. The operating system handles the fault by
 updating CSB with the following data:
 
 	csb.flags = CSB_V;
-	csb.cc = CSB_CC_TRANSLATION;
+	csb.cc = CSB_CC_FAULT_ADDRESS;
 	csb.ce = CSB_CE_TERMINATION;
 	csb.address = fault_address;
 

arch/powerpc/include/asm/icswx.h

@@ -77,6 +77,8 @@ struct coprocessor_completion_block {
 #define CSB_CC_CHAIN		(37)
 #define CSB_CC_SEQUENCE		(38)
 #define CSB_CC_HW		(39)
+/* P9 DD2 NX Workbook 3.2 (Table 4-36): Address translation fault */
+#define	CSB_CC_FAULT_ADDRESS	(250)
 
 #define CSB_SIZE		(0x10)
 #define CSB_ALIGN		CSB_SIZE

arch/powerpc/kernel/paca.c

@@ -87,7 +87,7 @@ static void *__init alloc_shared_lppaca(unsigned long size, unsigned long align,
 	 * This is very early in boot, so no harm done if the kernel crashes at
 	 * this point.
 	 */
-	BUG_ON(shared_lppaca_size >= shared_lppaca_total_size);
+	BUG_ON(shared_lppaca_size > shared_lppaca_total_size);
 
 	return ptr;
 }

arch/powerpc/mm/book3s64/pkeys.c

@@ -354,12 +354,14 @@ static bool pkey_access_permitted(int pkey, bool write, bool execute)
 	u64 amr;
 
 	pkey_shift = pkeyshift(pkey);
-	if (execute && !(read_iamr() & (IAMR_EX_BIT << pkey_shift)))
+	if (execute)
-		return true;
+		return !(read_iamr() & (IAMR_EX_BIT << pkey_shift));
 
-	amr = read_amr(); /* Delay reading amr until absolutely needed */
+	amr = read_amr();
-	return ((!write && !(amr & (AMR_RD_BIT << pkey_shift))) ||
+	if (write)
-		(write &&  !(amr & (AMR_WR_BIT << pkey_shift))));
+		return !(amr & (AMR_WR_BIT << pkey_shift));
+
+	return !(amr & (AMR_RD_BIT << pkey_shift));
 }
 
 bool arch_pte_access_permitted(u64 pte, bool write, bool execute)

arch/powerpc/platforms/powernv/vas-fault.c

@@ -79,7 +79,7 @@ static void update_csb(struct vas_window *window,
 	csb_addr = (void __user *)be64_to_cpu(crb->csb_addr);
 
 	memset(&csb, 0, sizeof(csb));
-	csb.cc = CSB_CC_TRANSLATION;
+	csb.cc = CSB_CC_FAULT_ADDRESS;
 	csb.ce = CSB_CE_TERMINATION;
 	csb.cs = 0;
 	csb.count = 0;

tools/testing/selftests/powerpc/nx-gzip/gunz_test.c

@@ -698,13 +698,13 @@ restart_nx:
 
 	switch (cc) {
 
-	case ERR_NX_TRANSLATION:
+	case ERR_NX_AT_FAULT:
 
 		/* We touched the pages ahead of time.  In the most common case
 		 * we shouldn't be here.  But may be some pages were paged out.
 		 * Kernel should have placed the faulting address to fsaddr.
 		 */
-		NXPRT(fprintf(stderr, "ERR_NX_TRANSLATION %p\n",
+		NXPRT(fprintf(stderr, "ERR_NX_AT_FAULT %p\n",
 			      (void *)cmdp->crb.csb.fsaddr));
 
 		if (pgfault_retries == NX_MAX_FAULTS) {

tools/testing/selftests/powerpc/nx-gzip/gzfht_test.c

@@ -306,13 +306,13 @@ int compress_file(int argc, char **argv, void *handle)
 			lzcounts, cmdp, handle);
 
 		if (cc != ERR_NX_OK && cc != ERR_NX_TPBC_GT_SPBC &&
-		    cc != ERR_NX_TRANSLATION) {
+		    cc != ERR_NX_AT_FAULT) {
 			fprintf(stderr, "nx error: cc= %d\n", cc);
 			exit(-1);
 		}
 
 		/* Page faults are handled by the user code */
-		if (cc == ERR_NX_TRANSLATION) {
+		if (cc == ERR_NX_AT_FAULT) {
 			NXPRT(fprintf(stderr, "page fault: cc= %d, ", cc));
 			NXPRT(fprintf(stderr, "try= %d, fsa= %08llx\n",
 				  fault_tries,