From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration Manually perform cache maintenance on the source VM during intra-host migration to ensure no stale data is left in CPU caches after the VM is destroyed. Because the source VM is "converted" to a non-SEV VM, KVM's memory reclaim flows won't trigger cache maintenance, e.g. when all guest memory is reclaimed in response to detaching from the mmu_notifier. Note, relying on the destination VM to do cache maintenance isn't an option as KVM doesn't require identical guest memory configurations, i.e. the source VM may have access to memory that the destination VM does not. Enforcing equivalent memory configurations is infeasible, as it would require a *deep* comparison of memslots, e.g. to verify that not only are the memslot identical, but what the memslots point at is also identical. Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration") Cc: stable@vger.kernel.org Reported-by: Stefan Teodorescu Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- drivers/base/auxiliary_sysfs.c | 113 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 113 insertions(+) create mode 100644 drivers/base/auxiliary_sysfs.c (limited to 'drivers/base/auxiliary_sysfs.c') diff --git a/drivers/base/auxiliary_sysfs.c b/drivers/base/auxiliary_sysfs.c new file mode 100644 index 000000000..dea7f46f7 --- /dev/null +++ b/drivers/base/auxiliary_sysfs.c @@ -0,0 +1,113 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2024, NVIDIA CORPORATION & AFFILIATES + */ + +#include +#include + +#define AUXILIARY_MAX_IRQ_NAME 11 + +struct auxiliary_irq_info { + struct device_attribute sysfs_attr; + char name[AUXILIARY_MAX_IRQ_NAME]; +}; + +static struct attribute *auxiliary_irq_attrs[] = { + NULL +}; + +static const struct attribute_group auxiliary_irqs_group = { + .name = "irqs", + .attrs = auxiliary_irq_attrs, +}; + +static int auxiliary_irq_dir_prepare(struct auxiliary_device *auxdev) +{ + int ret = 0; + + guard(mutex)(&auxdev->sysfs.lock); + if (auxdev->sysfs.irq_dir_exists) + return 0; + + ret = devm_device_add_group(&auxdev->dev, &auxiliary_irqs_group); + if (ret) + return ret; + + auxdev->sysfs.irq_dir_exists = true; + xa_init(&auxdev->sysfs.irqs); + return 0; +} + +/** + * auxiliary_device_sysfs_irq_add - add a sysfs entry for the given IRQ + * @auxdev: auxiliary bus device to add the sysfs entry. + * @irq: The associated interrupt number. + * + * This function should be called after auxiliary device have successfully + * received the irq. + * The driver is responsible to add a unique irq for the auxiliary device. The + * driver can invoke this function from multiple thread context safely for + * unique irqs of the auxiliary devices. The driver must not invoke this API + * multiple times if the irq is already added previously. + * + * Return: zero on success or an error code on failure. + */ +int auxiliary_device_sysfs_irq_add(struct auxiliary_device *auxdev, int irq) +{ + struct auxiliary_irq_info *info __free(kfree) = NULL; + struct device *dev = &auxdev->dev; + int ret; + + ret = auxiliary_irq_dir_prepare(auxdev); + if (ret) + return ret; + + info = kzalloc_obj(*info); + if (!info) + return -ENOMEM; + + sysfs_attr_init(&info->sysfs_attr.attr); + snprintf(info->name, AUXILIARY_MAX_IRQ_NAME, "%d", irq); + + ret = xa_insert(&auxdev->sysfs.irqs, irq, info, GFP_KERNEL); + if (ret) + return ret; + + info->sysfs_attr.attr.name = info->name; + ret = sysfs_add_file_to_group(&dev->kobj, &info->sysfs_attr.attr, + auxiliary_irqs_group.name); + if (ret) + goto sysfs_add_err; + + xa_store(&auxdev->sysfs.irqs, irq, no_free_ptr(info), GFP_KERNEL); + return 0; + +sysfs_add_err: + xa_erase(&auxdev->sysfs.irqs, irq); + return ret; +} +EXPORT_SYMBOL_GPL(auxiliary_device_sysfs_irq_add); + +/** + * auxiliary_device_sysfs_irq_remove - remove a sysfs entry for the given IRQ + * @auxdev: auxiliary bus device to add the sysfs entry. + * @irq: the IRQ to remove. + * + * This function should be called to remove an IRQ sysfs entry. + * The driver must invoke this API when IRQ is released by the device. + */ +void auxiliary_device_sysfs_irq_remove(struct auxiliary_device *auxdev, int irq) +{ + struct auxiliary_irq_info *info __free(kfree) = xa_load(&auxdev->sysfs.irqs, irq); + struct device *dev = &auxdev->dev; + + if (!info) { + dev_err(&auxdev->dev, "IRQ %d doesn't exist\n", irq); + return; + } + sysfs_remove_file_from_group(&dev->kobj, &info->sysfs_attr.attr, + auxiliary_irqs_group.name); + xa_erase(&auxdev->sysfs.irqs, irq); +} +EXPORT_SYMBOL_GPL(auxiliary_device_sysfs_irq_remove); -- cgit v1.3.1