* [PATCH 0/3] xen/privcmd: misc corrections
@ 2021-09-22 10:14 Jan Beulich
2021-09-22 10:16 ` [PATCH RFC 1/3] xen/privcmd: replace kcalloc() by kvcalloc() when allocating empty pages Jan Beulich
` (3 more replies)
0 siblings, 4 replies; 10+ messages in thread
From: Jan Beulich @ 2021-09-22 10:14 UTC (permalink / raw)
To: Juergen Gross, Boris Ostrovsky; +Cc: Stefano Stabellini, xen-devel, lkml
The three changes here are largely independent, except for a contextual
dependency between 2 and 3. Note that patch 1 will need actually testing,
on Arm.
1: replace kcalloc() by kvcalloc() when allocating empty pages
2: fix error handling in mmap-resource processing
3: drop "pages" parameter from xen_remap_pfn()
Jan
^ permalink raw reply [flat|nested] 10+ messages in thread* [PATCH RFC 1/3] xen/privcmd: replace kcalloc() by kvcalloc() when allocating empty pages 2021-09-22 10:14 [PATCH 0/3] xen/privcmd: misc corrections Jan Beulich @ 2021-09-22 10:16 ` Jan Beulich 2021-09-23 12:30 ` Juergen Gross 2021-09-22 10:17 ` [PATCH 2/3] xen/privcmd: fix error handling in mmap-resource processing Jan Beulich ` (2 subsequent siblings) 3 siblings, 1 reply; 10+ messages in thread From: Jan Beulich @ 2021-09-22 10:16 UTC (permalink / raw) To: Juergen Gross, Boris Ostrovsky; +Cc: Stefano Stabellini, xen-devel, lkml Osstest has been suffering test failures for a little while from order-4 allocation failures, resulting from alloc_empty_pages() calling kcalloc(). As there's no need for physically contiguous space here, switch to kvcalloc(). Signed-off-by: Jan Beulich <jbeulich@suse.com> --- RFC: I cannot really test this, as alloc_empty_pages() only gets used in the auto-translated case (i.e. on Arm or PVH Dom0, the latter of which I'm not trusting enough yet to actually start playing with guests). There are quite a few more kcalloc() where it's not immediately clear how large the element counts could possibly grow nor whether it would be fine to replace them (i.e. physically contiguous space not required). I wasn't sure whether to Cc stable@ here; the issue certainly has been present for quite some time. But it didn't look to cause issues until recently. --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -420,7 +420,7 @@ static int alloc_empty_pages(struct vm_a int rc; struct page **pages; - pages = kcalloc(numpgs, sizeof(pages[0]), GFP_KERNEL); + pages = kvcalloc(numpgs, sizeof(pages[0]), GFP_KERNEL); if (pages == NULL) return -ENOMEM; @@ -428,7 +428,7 @@ static int alloc_empty_pages(struct vm_a if (rc != 0) { pr_warn("%s Could not alloc %d pfns rc:%d\n", __func__, numpgs, rc); - kfree(pages); + kvfree(pages); return -ENOMEM; } BUG_ON(vma->vm_private_data != NULL); @@ -912,7 +912,7 @@ static void privcmd_close(struct vm_area else pr_crit("unable to unmap MFN range: leaking %d pages. rc=%d\n", numpgs, rc); - kfree(pages); + kvfree(pages); } static vm_fault_t privcmd_fault(struct vm_fault *vmf) ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH RFC 1/3] xen/privcmd: replace kcalloc() by kvcalloc() when allocating empty pages 2021-09-22 10:16 ` [PATCH RFC 1/3] xen/privcmd: replace kcalloc() by kvcalloc() when allocating empty pages Jan Beulich @ 2021-09-23 12:30 ` Juergen Gross 0 siblings, 0 replies; 10+ messages in thread From: Juergen Gross @ 2021-09-23 12:30 UTC (permalink / raw) To: Jan Beulich, Boris Ostrovsky; +Cc: Stefano Stabellini, xen-devel, lkml [-- Attachment #1.1.1: Type: text/plain, Size: 1209 bytes --] On 22.09.21 12:16, Jan Beulich wrote: > Osstest has been suffering test failures for a little while from order-4 > allocation failures, resulting from alloc_empty_pages() calling > kcalloc(). As there's no need for physically contiguous space here, > switch to kvcalloc(). > > Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Juergen Gross <jgross@suse.com> > --- > RFC: I cannot really test this, as alloc_empty_pages() only gets used in > the auto-translated case (i.e. on Arm or PVH Dom0, the latter of > which I'm not trusting enough yet to actually start playing with > guests). > > There are quite a few more kcalloc() where it's not immediately clear > how large the element counts could possibly grow nor whether it would be > fine to replace them (i.e. physically contiguous space not required). I don't think those are an issue. Per default the sizes seem to be well below a single page. > I wasn't sure whether to Cc stable@ here; the issue certainly has been > present for quite some time. But it didn't look to cause issues until > recently. I'd rather add it to stable. Its not as if the patch had a high complexity. Juergen [-- Attachment #1.1.2: OpenPGP public key --] [-- Type: application/pgp-keys, Size: 3135 bytes --] [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 495 bytes --] ^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH 2/3] xen/privcmd: fix error handling in mmap-resource processing 2021-09-22 10:14 [PATCH 0/3] xen/privcmd: misc corrections Jan Beulich 2021-09-22 10:16 ` [PATCH RFC 1/3] xen/privcmd: replace kcalloc() by kvcalloc() when allocating empty pages Jan Beulich @ 2021-09-22 10:17 ` Jan Beulich 2021-09-22 13:29 ` Boris Ostrovsky 2021-09-22 10:18 ` [PATCH 3/3] xen/privcmd: drop "pages" parameter from xen_remap_pfn() Jan Beulich 2021-10-05 6:39 ` [PATCH 0/3] xen/privcmd: misc corrections Juergen Gross 3 siblings, 1 reply; 10+ messages in thread From: Jan Beulich @ 2021-09-22 10:17 UTC (permalink / raw) To: Juergen Gross, Boris Ostrovsky; +Cc: Stefano Stabellini, xen-devel, lkml xen_pfn_t is the same size as int only on 32-bit builds (and not even on Arm32). Hence pfns[] can't be used directly to read individual error values returned from xen_remap_domain_mfn_array(); every other error indicator would be skipped/ignored on 64-bit. Fixes: 3ad0876554ca ("xen/privcmd: add IOCTL_PRIVCMD_MMAP_RESOURCE") Cc: stable@vger.kernel.org Signed-off-by: Jan Beulich <jbeulich@suse.com> --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -803,11 +803,12 @@ static long privcmd_ioctl_mmap_resource( unsigned int domid = (xdata.flags & XENMEM_rsrc_acq_caller_owned) ? DOMID_SELF : kdata.dom; - int num; + int num, *errs = (int *)pfns; + BUILD_BUG_ON(sizeof(*errs) > sizeof(*pfns)); num = xen_remap_domain_mfn_array(vma, kdata.addr & PAGE_MASK, - pfns, kdata.num, (int *)pfns, + pfns, kdata.num, errs, vma->vm_page_prot, domid, vma->vm_private_data); @@ -817,7 +818,7 @@ static long privcmd_ioctl_mmap_resource( unsigned int i; for (i = 0; i < num; i++) { - rc = pfns[i]; + rc = errs[i]; if (rc < 0) break; } ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 2/3] xen/privcmd: fix error handling in mmap-resource processing 2021-09-22 10:17 ` [PATCH 2/3] xen/privcmd: fix error handling in mmap-resource processing Jan Beulich @ 2021-09-22 13:29 ` Boris Ostrovsky 2021-09-22 13:39 ` Jan Beulich 0 siblings, 1 reply; 10+ messages in thread From: Boris Ostrovsky @ 2021-09-22 13:29 UTC (permalink / raw) To: Jan Beulich, Juergen Gross; +Cc: Stefano Stabellini, xen-devel, lkml On 9/22/21 6:17 AM, Jan Beulich wrote: > @@ -817,7 +818,7 @@ static long privcmd_ioctl_mmap_resource( > unsigned int i; > > for (i = 0; i < num; i++) { > - rc = pfns[i]; > + rc = errs[i]; > if (rc < 0) > break; Can the assignment be moved inside the 'if' statement? I am also not sure I understand why we need error array at all. Don't we always look at the first error only? In fact, AFAICS this is the only place where we look at the value. -boris ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 2/3] xen/privcmd: fix error handling in mmap-resource processing 2021-09-22 13:29 ` Boris Ostrovsky @ 2021-09-22 13:39 ` Jan Beulich 2021-09-22 13:56 ` Boris Ostrovsky 0 siblings, 1 reply; 10+ messages in thread From: Jan Beulich @ 2021-09-22 13:39 UTC (permalink / raw) To: Boris Ostrovsky; +Cc: Stefano Stabellini, xen-devel, lkml, Juergen Gross On 22.09.2021 15:29, Boris Ostrovsky wrote: > On 9/22/21 6:17 AM, Jan Beulich wrote: >> @@ -817,7 +818,7 @@ static long privcmd_ioctl_mmap_resource( >> unsigned int i; >> >> for (i = 0; i < num; i++) { >> - rc = pfns[i]; >> + rc = errs[i]; >> if (rc < 0) >> break; > > > Can the assignment be moved inside the 'if' statement? I wouldn't mind, albeit it's not the purpose of this change. Plus generally, when I do such elsewhere, I'm frequently told to better leave things as separate statements. IOW I'm a little surprised by the request. > I am also not sure I understand why we need error array at all. Don't we always look at the first error only? In fact, AFAICS this is the only place where we look at the value. Well, to look at the first error we need to scan the array to find one. Indeed we bail from here in once we've found a slot which has failed. I guess what you're trying to say is that there's room for improvement. In which case I might agree, but would want to point out that doing so would mean removing flexibility from the underlying function(s) (which may or may not be fine depending on what existing and future requirements there are). And that would be for another day, if at all. Jan ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 2/3] xen/privcmd: fix error handling in mmap-resource processing 2021-09-22 13:39 ` Jan Beulich @ 2021-09-22 13:56 ` Boris Ostrovsky 0 siblings, 0 replies; 10+ messages in thread From: Boris Ostrovsky @ 2021-09-22 13:56 UTC (permalink / raw) To: Jan Beulich; +Cc: Stefano Stabellini, xen-devel, lkml, Juergen Gross On 9/22/21 9:39 AM, Jan Beulich wrote: > On 22.09.2021 15:29, Boris Ostrovsky wrote: >> On 9/22/21 6:17 AM, Jan Beulich wrote: >>> @@ -817,7 +818,7 @@ static long privcmd_ioctl_mmap_resource( >>> unsigned int i; >>> >>> for (i = 0; i < num; i++) { >>> - rc = pfns[i]; >>> + rc = errs[i]; >>> if (rc < 0) >>> break; >> >> Can the assignment be moved inside the 'if' statement? > I wouldn't mind, albeit it's not the purpose of this change. Plus > generally, when I do such elsewhere, I'm frequently told to better > leave things as separate statements. IOW I'm a little surprised by > the request. Sure, can be done as a separate patch. Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> > >> I am also not sure I understand why we need error array at all. Don't we always look at the first error only? In fact, AFAICS this is the only place where we look at the value. > Well, to look at the first error we need to scan the array to find > one. Indeed we bail from here in once we've found a slot which has > failed. > > I guess what you're trying to say is that there's room for > improvement. In which case I might agree, but would want to point > out that doing so would mean removing flexibility from the > underlying function(s) (which may or may not be fine depending on > what existing and future requirements there are). We haven't needed this for a while and IMO existing code, with overloading the meaning of the pfn array, is rather confusing, unnecessarily complicated and error-prone (thus your patch). > And that would > be for another day, if at all. True. ^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH 3/3] xen/privcmd: drop "pages" parameter from xen_remap_pfn() 2021-09-22 10:14 [PATCH 0/3] xen/privcmd: misc corrections Jan Beulich 2021-09-22 10:16 ` [PATCH RFC 1/3] xen/privcmd: replace kcalloc() by kvcalloc() when allocating empty pages Jan Beulich 2021-09-22 10:17 ` [PATCH 2/3] xen/privcmd: fix error handling in mmap-resource processing Jan Beulich @ 2021-09-22 10:18 ` Jan Beulich 2021-09-22 14:02 ` Boris Ostrovsky 2021-10-05 6:39 ` [PATCH 0/3] xen/privcmd: misc corrections Juergen Gross 3 siblings, 1 reply; 10+ messages in thread From: Jan Beulich @ 2021-09-22 10:18 UTC (permalink / raw) To: Juergen Gross, Boris Ostrovsky; +Cc: Stefano Stabellini, xen-devel, lkml The function doesn't use it and all of its callers say in a comment that their respective arguments are to be non-NULL only in auto-translated mode. Since xen_remap_domain_mfn_array() isn't supposed to be used by non-PV, drop the parameter there as well. It was bogusly passed as non- NULL (PRIV_VMA_LOCKED) by its only caller anyway. For xen_remap_domain_gfn_range(), otoh, it's not clear at all why this wouldn't want / might not need to gain auto-translated support down the road, so the parameter is retained there despite now remaining unused (and the only caller passing NULL); correct a respective comment as well. Signed-off-by: Jan Beulich <jbeulich@suse.com> --- a/arch/x86/xen/mmu_pv.c +++ b/arch/x86/xen/mmu_pv.c @@ -2398,7 +2398,7 @@ static int remap_area_pfn_pte_fn(pte_t * int xen_remap_pfn(struct vm_area_struct *vma, unsigned long addr, xen_pfn_t *pfn, int nr, int *err_ptr, pgprot_t prot, - unsigned int domid, bool no_translate, struct page **pages) + unsigned int domid, bool no_translate) { int err = 0; struct remap_data rmd; --- a/drivers/xen/privcmd.c +++ b/drivers/xen/privcmd.c @@ -257,7 +257,7 @@ static long privcmd_ioctl_mmap(struct fi LIST_HEAD(pagelist); struct mmap_gfn_state state; - /* We only support privcmd_ioctl_mmap_batch for auto translated. */ + /* We only support privcmd_ioctl_mmap_batch for non-auto-translated. */ if (xen_feature(XENFEAT_auto_translated_physmap)) return -ENOSYS; @@ -810,8 +810,7 @@ static long privcmd_ioctl_mmap_resource( kdata.addr & PAGE_MASK, pfns, kdata.num, errs, vma->vm_page_prot, - domid, - vma->vm_private_data); + domid); if (num < 0) rc = num; else if (num != kdata.num) { --- a/include/xen/xen-ops.h +++ b/include/xen/xen-ops.h @@ -64,12 +64,12 @@ static inline void xen_destroy_contiguou #if defined(CONFIG_XEN_PV) int xen_remap_pfn(struct vm_area_struct *vma, unsigned long addr, xen_pfn_t *pfn, int nr, int *err_ptr, pgprot_t prot, - unsigned int domid, bool no_translate, struct page **pages); + unsigned int domid, bool no_translate); #else static inline int xen_remap_pfn(struct vm_area_struct *vma, unsigned long addr, xen_pfn_t *pfn, int nr, int *err_ptr, pgprot_t prot, unsigned int domid, - bool no_translate, struct page **pages) + bool no_translate) { BUG(); return 0; @@ -146,7 +146,7 @@ static inline int xen_remap_domain_gfn_a */ BUG_ON(err_ptr == NULL); return xen_remap_pfn(vma, addr, gfn, nr, err_ptr, prot, domid, - false, pages); + false); } /* @@ -158,7 +158,6 @@ static inline int xen_remap_domain_gfn_a * @err_ptr: Returns per-MFN error status. * @prot: page protection mask * @domid: Domain owning the pages - * @pages: Array of pages if this domain has an auto-translated physmap * * @mfn and @err_ptr may point to the same buffer, the MFNs will be * overwritten by the error codes after they are mapped. @@ -169,14 +168,13 @@ static inline int xen_remap_domain_gfn_a static inline int xen_remap_domain_mfn_array(struct vm_area_struct *vma, unsigned long addr, xen_pfn_t *mfn, int nr, int *err_ptr, - pgprot_t prot, unsigned int domid, - struct page **pages) + pgprot_t prot, unsigned int domid) { if (xen_feature(XENFEAT_auto_translated_physmap)) return -EOPNOTSUPP; return xen_remap_pfn(vma, addr, mfn, nr, err_ptr, prot, domid, - true, pages); + true); } /* xen_remap_domain_gfn_range() - map a range of foreign frames @@ -200,8 +198,7 @@ static inline int xen_remap_domain_gfn_r if (xen_feature(XENFEAT_auto_translated_physmap)) return -EOPNOTSUPP; - return xen_remap_pfn(vma, addr, &gfn, nr, NULL, prot, domid, false, - pages); + return xen_remap_pfn(vma, addr, &gfn, nr, NULL, prot, domid, false); } int xen_unmap_domain_gfn_range(struct vm_area_struct *vma, ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 3/3] xen/privcmd: drop "pages" parameter from xen_remap_pfn() 2021-09-22 10:18 ` [PATCH 3/3] xen/privcmd: drop "pages" parameter from xen_remap_pfn() Jan Beulich @ 2021-09-22 14:02 ` Boris Ostrovsky 0 siblings, 0 replies; 10+ messages in thread From: Boris Ostrovsky @ 2021-09-22 14:02 UTC (permalink / raw) To: Jan Beulich, Juergen Gross; +Cc: Stefano Stabellini, xen-devel, lkml On 9/22/21 6:18 AM, Jan Beulich wrote: > The function doesn't use it and all of its callers say in a comment that > their respective arguments are to be non-NULL only in auto-translated > mode. Since xen_remap_domain_mfn_array() isn't supposed to be used by > non-PV, drop the parameter there as well. It was bogusly passed as non- > NULL (PRIV_VMA_LOCKED) by its only caller anyway. For > xen_remap_domain_gfn_range(), otoh, it's not clear at all why this > wouldn't want / might not need to gain auto-translated support down the > road, so the parameter is retained there despite now remaining unused > (and the only caller passing NULL); correct a respective comment as > well. > > Signed-off-by: Jan Beulich <jbeulich@suse.com> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 0/3] xen/privcmd: misc corrections 2021-09-22 10:14 [PATCH 0/3] xen/privcmd: misc corrections Jan Beulich ` (2 preceding siblings ...) 2021-09-22 10:18 ` [PATCH 3/3] xen/privcmd: drop "pages" parameter from xen_remap_pfn() Jan Beulich @ 2021-10-05 6:39 ` Juergen Gross 3 siblings, 0 replies; 10+ messages in thread From: Juergen Gross @ 2021-10-05 6:39 UTC (permalink / raw) To: Jan Beulich, Boris Ostrovsky; +Cc: Stefano Stabellini, xen-devel, lkml [-- Attachment #1.1.1: Type: text/plain, Size: 438 bytes --] On 22.09.21 12:14, Jan Beulich wrote: > The three changes here are largely independent, except for a contextual > dependency between 2 and 3. Note that patch 1 will need actually testing, > on Arm. > > 1: replace kcalloc() by kvcalloc() when allocating empty pages > 2: fix error handling in mmap-resource processing > 3: drop "pages" parameter from xen_remap_pfn() Series pushed to xen/tip.git for-linus-5.15b Juergen [-- Attachment #1.1.2: OpenPGP public key --] [-- Type: application/pgp-keys, Size: 3135 bytes --] [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 495 bytes --] ^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2021-10-05 6:39 UTC | newest] Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-09-22 10:14 [PATCH 0/3] xen/privcmd: misc corrections Jan Beulich 2021-09-22 10:16 ` [PATCH RFC 1/3] xen/privcmd: replace kcalloc() by kvcalloc() when allocating empty pages Jan Beulich 2021-09-23 12:30 ` Juergen Gross 2021-09-22 10:17 ` [PATCH 2/3] xen/privcmd: fix error handling in mmap-resource processing Jan Beulich 2021-09-22 13:29 ` Boris Ostrovsky 2021-09-22 13:39 ` Jan Beulich 2021-09-22 13:56 ` Boris Ostrovsky 2021-09-22 10:18 ` [PATCH 3/3] xen/privcmd: drop "pages" parameter from xen_remap_pfn() Jan Beulich 2021-09-22 14:02 ` Boris Ostrovsky 2021-10-05 6:39 ` [PATCH 0/3] xen/privcmd: misc corrections Juergen Gross
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