From cdf9df020130237edf8860187aca3636d679aa48 Mon Sep 17 00:00:00 2001 From: Uros Bizjak Date: Fri, 5 Apr 2024 10:32:53 +0200 Subject: locking/x86/xen: Use try_cmpxchg() in xen_alloc_p2m_entry() Use try_cmpxchg() instead of cmpxchg(*ptr, old, new) == old. The x86 CMPXCHG instruction returns success in the ZF flag, so this change saves a compare after CMPXCHG. Also, try_cmpxchg() implicitly assigns old *ptr value to "old" when CMPXCHG fails. There is no need to explicitly assign old *ptr value to the temporary, which can simplify the surrounding source code. No functional change intended. Signed-off-by: Uros Bizjak Reviewed-by: Juergen Gross Cc: Juergen Gross Cc: Boris Ostrovsky Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" Link: https://lore.kernel.org/r/20240405083335.507471-1-ubizjak@gmail.com Signed-off-by: Juergen Gross --- arch/x86/xen/p2m.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index 9bdc3b656b2c..99918beccd80 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -555,7 +555,6 @@ int xen_alloc_p2m_entry(unsigned long pfn) /* Separately check the mid mfn level */ unsigned long missing_mfn; unsigned long mid_mfn_mfn; - unsigned long old_mfn; mid_mfn = alloc_p2m_page(); if (!mid_mfn) @@ -565,12 +564,12 @@ int xen_alloc_p2m_entry(unsigned long pfn) missing_mfn = virt_to_mfn(p2m_mid_missing_mfn); mid_mfn_mfn = virt_to_mfn(mid_mfn); - old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn); - if (old_mfn != missing_mfn) { - free_p2m_page(mid_mfn); - mid_mfn = mfn_to_virt(old_mfn); - } else { + /* try_cmpxchg() updates missing_mfn on failure. */ + if (try_cmpxchg(top_mfn_p, &missing_mfn, mid_mfn_mfn)) { p2m_top_mfn_p[topidx] = mid_mfn; + } else { + free_p2m_page(mid_mfn); + mid_mfn = mfn_to_virt(missing_mfn); } } } else { -- cgit v1.2.3 From a6aa4eb994ee9ced905743817c5de8451d26b911 Mon Sep 17 00:00:00 2001 From: Roger Pau Monne Date: Mon, 29 Apr 2024 17:50:53 +0200 Subject: xen/x86: add extra pages to unpopulated-alloc if available MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Commit 262fc47ac174 ('xen/balloon: don't use PV mode extra memory for zone device allocations') removed the addition of the extra memory ranges to the unpopulated range allocator, using those only for the balloon driver. This forces the unpopulated allocator to attach hotplug ranges even when spare memory (as part of the extra memory ranges) is available. Furthermore, on PVH domains it defeats the purpose of commit 38620fc4e893 ('x86/xen: attempt to inflate the memory balloon on PVH'), as extra memory ranges would only be used to map foreign memory if the kernel is built without XEN_UNPOPULATED_ALLOC support. Fix this by adding a helpers that adds the extra memory ranges to the list of unpopulated pages, and zeroes the ranges so they are not also consumed by the balloon driver. This should have been part of 38620fc4e893, hence the fixes tag. Note the current logic relies on unpopulated_init() (and hence arch_xen_unpopulated_init()) always being called ahead of balloon_init(), so that the extra memory regions are consumed by arch_xen_unpopulated_init(). Fixes: 38620fc4e893 ('x86/xen: attempt to inflate the memory balloon on PVH') Signed-off-by: Roger Pau Monné Reviewed-by: Juergen Gross Link: https://lore.kernel.org/r/20240429155053.72509-1-roger.pau@citrix.com Signed-off-by: Juergen Gross --- arch/x86/xen/enlighten.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index a01ca255b0c6..b88722dfc4f8 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -382,3 +382,36 @@ void __init xen_add_extra_mem(unsigned long start_pfn, unsigned long n_pfns) memblock_reserve(PFN_PHYS(start_pfn), PFN_PHYS(n_pfns)); } + +#ifdef CONFIG_XEN_UNPOPULATED_ALLOC +int __init arch_xen_unpopulated_init(struct resource **res) +{ + unsigned int i; + + if (!xen_domain()) + return -ENODEV; + + /* Must be set strictly before calling xen_free_unpopulated_pages(). */ + *res = &iomem_resource; + + /* + * Initialize with pages from the extra memory regions (see + * arch/x86/xen/setup.c). + */ + for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) { + unsigned int j; + + for (j = 0; j < xen_extra_mem[i].n_pfns; j++) { + struct page *pg = + pfn_to_page(xen_extra_mem[i].start_pfn + j); + + xen_free_unpopulated_pages(1, &pg); + } + + /* Zero so region is not also added to the balloon driver. */ + xen_extra_mem[i].n_pfns = 0; + } + + return 0; +} +#endif -- cgit v1.2.3 From 89af61fb8f0f96646e1462246a825c1268ba70ba Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Wed, 8 May 2024 18:26:47 +0300 Subject: xen/xenbus: Use *-y instead of *-objs in Makefile *-objs suffix is reserved rather for (user-space) host programs while usually *-y suffix is used for kernel drivers (although *-objs works for that purpose for now). Let's correct the old usages of *-objs in Makefiles. Signed-off-by: Andy Shevchenko Acked-by: Juergen Gross Link: https://lore.kernel.org/r/20240508152658.1445809-1-andriy.shevchenko@linux.intel.com Signed-off-by: Juergen Gross --- drivers/xen/xenbus/Makefile | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/drivers/xen/xenbus/Makefile b/drivers/xen/xenbus/Makefile index 0c7532110815..b0d69602214e 100644 --- a/drivers/xen/xenbus/Makefile +++ b/drivers/xen/xenbus/Makefile @@ -1,15 +1,13 @@ # SPDX-License-Identifier: GPL-2.0 obj-y += xenbus.o -obj-y += xenbus_dev_frontend.o -xenbus-objs = -xenbus-objs += xenbus_client.o -xenbus-objs += xenbus_comms.o -xenbus-objs += xenbus_xs.o -xenbus-objs += xenbus_probe.o +xenbus-y := xenbus_client.o +xenbus-y += xenbus_comms.o +xenbus-y += xenbus_xs.o +xenbus-y += xenbus_probe.o -xenbus-be-objs-$(CONFIG_XEN_BACKEND) += xenbus_probe_backend.o -xenbus-objs += $(xenbus-be-objs-y) +xenbus-$(CONFIG_XEN_BACKEND) += xenbus_probe_backend.o +obj-y += xenbus_dev_frontend.o obj-$(CONFIG_XEN_BACKEND) += xenbus_dev_backend.o obj-$(CONFIG_XEN_XENBUS_FRONTEND) += xenbus_probe_frontend.o -- cgit v1.2.3 From a3607581cd49c17128a486a526a36a97bafcb2bb Mon Sep 17 00:00:00 2001 From: Henry Wang Date: Fri, 17 May 2024 09:15:16 +0800 Subject: drivers/xen: Improve the late XenStore init protocol Currently, the late XenStore init protocol is only triggered properly for the case that HVM_PARAM_STORE_PFN is ~0ULL (invalid). For the case that XenStore interface is allocated but not ready (the connection status is not XENSTORE_CONNECTED), Linux should also wait until the XenStore is set up properly. Introduce a macro to describe the XenStore interface is ready, use it in xenbus_probe_initcall() to select the code path of doing the late XenStore init protocol or not. Since now we have more than one condition for XenStore late init, rework the check in xenbus_probe() for the free_irq(). Take the opportunity to enhance the check of the allocated XenStore interface can be properly mapped, and return error early if the memremap() fails. Fixes: 5b3353949e89 ("xen: add support for initializing xenstore later as HVM domain") Signed-off-by: Henry Wang Signed-off-by: Michal Orzel Reviewed-by: Stefano Stabellini Link: https://lore.kernel.org/r/20240517011516.1451087-1-xin.wang2@amd.com Signed-off-by: Juergen Gross --- drivers/xen/xenbus/xenbus_probe.c | 36 +++++++++++++++++++++++------------- 1 file changed, 23 insertions(+), 13 deletions(-) diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c index 3205e5d724c8..1a9ded0cddcb 100644 --- a/drivers/xen/xenbus/xenbus_probe.c +++ b/drivers/xen/xenbus/xenbus_probe.c @@ -65,13 +65,17 @@ #include "xenbus.h" -static int xs_init_irq; +static int xs_init_irq = -1; int xen_store_evtchn; EXPORT_SYMBOL_GPL(xen_store_evtchn); struct xenstore_domain_interface *xen_store_interface; EXPORT_SYMBOL_GPL(xen_store_interface); +#define XS_INTERFACE_READY \ + ((xen_store_interface != NULL) && \ + (xen_store_interface->connection == XENSTORE_CONNECTED)) + enum xenstore_init xen_store_domain_type; EXPORT_SYMBOL_GPL(xen_store_domain_type); @@ -751,19 +755,19 @@ static void xenbus_probe(void) { xenstored_ready = 1; - if (!xen_store_interface) { + if (!xen_store_interface) xen_store_interface = memremap(xen_store_gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE, MEMREMAP_WB); - /* - * Now it is safe to free the IRQ used for xenstore late - * initialization. No need to unbind: it is about to be - * bound again from xb_init_comms. Note that calling - * unbind_from_irqhandler now would result in xen_evtchn_close() - * being called and the event channel not being enabled again - * afterwards, resulting in missed event notifications. - */ + /* + * Now it is safe to free the IRQ used for xenstore late + * initialization. No need to unbind: it is about to be + * bound again from xb_init_comms. Note that calling + * unbind_from_irqhandler now would result in xen_evtchn_close() + * being called and the event channel not being enabled again + * afterwards, resulting in missed event notifications. + */ + if (xs_init_irq >= 0) free_irq(xs_init_irq, &xb_waitq); - } /* * In the HVM case, xenbus_init() deferred its call to @@ -822,7 +826,7 @@ static int __init xenbus_probe_initcall(void) if (xen_store_domain_type == XS_PV || (xen_store_domain_type == XS_HVM && !xs_hvm_defer_init_for_callback() && - xen_store_interface != NULL)) + XS_INTERFACE_READY)) xenbus_probe(); /* @@ -831,7 +835,7 @@ static int __init xenbus_probe_initcall(void) * started, then probe. It will be triggered when communication * starts happening, by waiting on xb_waitq. */ - if (xen_store_domain_type == XS_LOCAL || xen_store_interface == NULL) { + if (xen_store_domain_type == XS_LOCAL || !XS_INTERFACE_READY) { struct task_struct *probe_task; probe_task = kthread_run(xenbus_probe_thread, NULL, @@ -1014,6 +1018,12 @@ static int __init xenbus_init(void) xen_store_interface = memremap(xen_store_gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE, MEMREMAP_WB); + if (!xen_store_interface) { + pr_err("%s: cannot map HVM_PARAM_STORE_PFN=%llx\n", + __func__, v); + err = -EINVAL; + goto out_error; + } if (xen_store_interface->connection != XENSTORE_CONNECTED) wait = true; } -- cgit v1.2.3