Re: [PATCH v3 08/14] powerpc: add support for folded p4d page tables

Friday, 28 February 2020

Hi Mike,

I love your patch! Yet something to improve:

[auto build test ERROR on powerpc/next]
[also build test ERROR on arm/for-next arm64/for-next/core linus/master v5.6-rc3
next-20200228]
[cannot apply to mmotm/master]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:   
https://github.com/0day-ci/linux/commits/Mike-Rapoport/mm-remove-__ARCH_H...
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-ppc64_defconfig (attached as .config)
compiler: powerpc64-linux-gcc (GCC) 7.5.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.5.0 make.cross ARCH=powerpc 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp(a)intel.com&gt;

All errors (new ones prefixed by >>):

   arch/powerpc/kvm/book3s_64_mmu_radix.c: In function 'debugfs_radix_read':
...
> arch/powerpc/kvm/book3s_64_mmu_radix.c:1226:8: error: unused
variable 'pgd' [-Werror=unused-variable]      pgd_t pgd, *pgdp;
           ^~~
   cc1: all warnings being treated as errors

vim +/pgd +1226 arch/powerpc/kvm/book3s_64_mmu_radix.c

9a94d3ee2d1599 Paul Mackerras 2018-10-08  1215  
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1216  static ssize_t debugfs_radix_read(struct
file *file, char __user *buf,
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1217  				 size_t len, loff_t *ppos)
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1218  {
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1219  	struct debugfs_radix_state *p =
file->private_data;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1220  	ssize_t ret, r;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1221  	unsigned long n;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1222  	struct kvm *kvm;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1223  	unsigned long gpa;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1224  	pgd_t *pgt;
83a055104eaf89 Paul Mackerras 2018-10-08  1225  	struct kvm_nested_guest *nested;
9a94d3ee2d1599 Paul Mackerras 2018-10-08 @1226  	pgd_t pgd, *pgdp;
f97ba1f7bf6bd7 Mike Rapoport  2020-02-27  1227  	p4d_t p4d, *p4dp;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1228  	pud_t pud, *pudp;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1229  	pmd_t pmd, *pmdp;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1230  	pte_t *ptep;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1231  	int shift;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1232  	unsigned long pte;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1233  
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1234  	kvm = p->kvm;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1235  	if (!kvm_is_radix(kvm))
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1236  		return 0;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1237  
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1238  	ret =
mutex_lock_interruptible(&p->mutex);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1239  	if (ret)
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1240  		return ret;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1241  
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1242  	if (p->chars_left) {
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1243  		n = p->chars_left;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1244  		if (n > len)
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1245  			n = len;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1246  		r = copy_to_user(buf, p->buf +
p->buf_index, n);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1247  		n -= r;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1248  		p->chars_left -= n;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1249  		p->buf_index += n;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1250  		buf += n;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1251  		len -= n;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1252  		ret = n;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1253  		if (r) {
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1254  			if (!n)
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1255  				ret = -EFAULT;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1256  			goto out;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1257  		}
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1258  	}
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1259  
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1260  	gpa = p->gpa;
83a055104eaf89 Paul Mackerras 2018-10-08  1261  	nested = NULL;
83a055104eaf89 Paul Mackerras 2018-10-08  1262  	pgt = NULL;
83a055104eaf89 Paul Mackerras 2018-10-08  1263  	while (len != 0 && p->lpid
>= 0) {
83a055104eaf89 Paul Mackerras 2018-10-08  1264  		if (gpa >= RADIX_PGTABLE_RANGE) {
83a055104eaf89 Paul Mackerras 2018-10-08  1265  			gpa = 0;
83a055104eaf89 Paul Mackerras 2018-10-08  1266  			pgt = NULL;
83a055104eaf89 Paul Mackerras 2018-10-08  1267  			if (nested) {
83a055104eaf89 Paul Mackerras 2018-10-08  1268  				kvmhv_put_nested(nested);
83a055104eaf89 Paul Mackerras 2018-10-08  1269  				nested = NULL;
83a055104eaf89 Paul Mackerras 2018-10-08  1270  			}
83a055104eaf89 Paul Mackerras 2018-10-08  1271  			p->lpid =
kvmhv_nested_next_lpid(kvm, p->lpid);
83a055104eaf89 Paul Mackerras 2018-10-08  1272  			p->hdr = 0;
83a055104eaf89 Paul Mackerras 2018-10-08  1273  			if (p->lpid < 0)
83a055104eaf89 Paul Mackerras 2018-10-08  1274  				break;
83a055104eaf89 Paul Mackerras 2018-10-08  1275  		}
83a055104eaf89 Paul Mackerras 2018-10-08  1276  		if (!pgt) {
83a055104eaf89 Paul Mackerras 2018-10-08  1277  			if (p->lpid == 0) {
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1278  				pgt = kvm->arch.pgtable;
83a055104eaf89 Paul Mackerras 2018-10-08  1279  			} else {
83a055104eaf89 Paul Mackerras 2018-10-08  1280  				nested = kvmhv_get_nested(kvm,
p->lpid, false);
83a055104eaf89 Paul Mackerras 2018-10-08  1281  				if (!nested) {
83a055104eaf89 Paul Mackerras 2018-10-08  1282  					gpa = RADIX_PGTABLE_RANGE;
83a055104eaf89 Paul Mackerras 2018-10-08  1283  					continue;
83a055104eaf89 Paul Mackerras 2018-10-08  1284  				}
83a055104eaf89 Paul Mackerras 2018-10-08  1285  				pgt = nested->shadow_pgtable;
83a055104eaf89 Paul Mackerras 2018-10-08  1286  			}
83a055104eaf89 Paul Mackerras 2018-10-08  1287  		}
83a055104eaf89 Paul Mackerras 2018-10-08  1288  		n = 0;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1289  		if (!p->hdr) {
83a055104eaf89 Paul Mackerras 2018-10-08  1290  			if (p->lpid > 0)
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1291  				n = scnprintf(p->buf,
sizeof(p->buf),
83a055104eaf89 Paul Mackerras 2018-10-08  1292  					      "\nNested LPID %d: ",
p->lpid);
83a055104eaf89 Paul Mackerras 2018-10-08  1293  			n += scnprintf(p->buf + n,
sizeof(p->buf) - n,
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1294  				      "pgdir: %lx\n",
(unsigned long)pgt);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1295  			p->hdr = 1;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1296  			goto copy;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1297  		}
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1298  
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1299  		pgdp = pgt + pgd_index(gpa);
f97ba1f7bf6bd7 Mike Rapoport  2020-02-27  1300  		p4dp = p4d_offset(pgdp, gpa);
f97ba1f7bf6bd7 Mike Rapoport  2020-02-27  1301  		p4d = READ_ONCE(*p4dp);
f97ba1f7bf6bd7 Mike Rapoport  2020-02-27  1302  		if (!(p4d_val(p4d) & _PAGE_PRESENT))
{
f97ba1f7bf6bd7 Mike Rapoport  2020-02-27  1303  			gpa = (gpa & P4D_MASK) + P4D_SIZE;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1304  			continue;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1305  		}
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1306  
f97ba1f7bf6bd7 Mike Rapoport  2020-02-27  1307  		pudp = pud_offset(&p4d, gpa);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1308  		pud = READ_ONCE(*pudp);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1309  		if (!(pud_val(pud) & _PAGE_PRESENT))
{
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1310  			gpa = (gpa & PUD_MASK) + PUD_SIZE;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1311  			continue;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1312  		}
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1313  		if (pud_val(pud) & _PAGE_PTE) {
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1314  			pte = pud_val(pud);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1315  			shift = PUD_SHIFT;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1316  			goto leaf;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1317  		}
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1318  
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1319  		pmdp = pmd_offset(&pud, gpa);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1320  		pmd = READ_ONCE(*pmdp);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1321  		if (!(pmd_val(pmd) & _PAGE_PRESENT))
{
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1322  			gpa = (gpa & PMD_MASK) + PMD_SIZE;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1323  			continue;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1324  		}
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1325  		if (pmd_val(pmd) & _PAGE_PTE) {
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1326  			pte = pmd_val(pmd);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1327  			shift = PMD_SHIFT;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1328  			goto leaf;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1329  		}
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1330  
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1331  		ptep = pte_offset_kernel(&pmd,
gpa);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1332  		pte = pte_val(READ_ONCE(*ptep));
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1333  		if (!(pte & _PAGE_PRESENT)) {
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1334  			gpa += PAGE_SIZE;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1335  			continue;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1336  		}
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1337  		shift = PAGE_SHIFT;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1338  	leaf:
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1339  		n = scnprintf(p->buf,
sizeof(p->buf),
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1340  			      " %lx: %lx %d\n", gpa,
pte, shift);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1341  		gpa += 1ul << shift;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1342  	copy:
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1343  		p->chars_left = n;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1344  		if (n > len)
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1345  			n = len;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1346  		r = copy_to_user(buf, p->buf, n);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1347  		n -= r;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1348  		p->chars_left -= n;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1349  		p->buf_index = n;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1350  		buf += n;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1351  		len -= n;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1352  		ret += n;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1353  		if (r) {
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1354  			if (!ret)
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1355  				ret = -EFAULT;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1356  			break;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1357  		}
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1358  	}
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1359  	p->gpa = gpa;
83a055104eaf89 Paul Mackerras 2018-10-08  1360  	if (nested)
83a055104eaf89 Paul Mackerras 2018-10-08  1361  		kvmhv_put_nested(nested);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1362  
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1363   out:
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1364  	mutex_unlock(&p->mutex);
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1365  	return ret;
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1366  }
9a94d3ee2d1599 Paul Mackerras 2018-10-08  1367  

:::::: The code at line 1226 was first introduced by commit
:::::: 9a94d3ee2d159927c0f8e5078228eadbce8dda43 KVM: PPC: Book3S HV: Add a debugfs file to
dump radix mappings

:::::: TO: Paul Mackerras <paulus(a)ozlabs.org&gt;
:::::: CC: Michael Ellerman <mpe(a)ellerman.id.au&gt;

---
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