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/nvmem/apple-efuses.c | 81 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 drivers/nvmem/apple-efuses.c (limited to 'drivers/nvmem/apple-efuses.c') diff --git a/drivers/nvmem/apple-efuses.c b/drivers/nvmem/apple-efuses.c new file mode 100644 index 000000000..9913e77b8 --- /dev/null +++ b/drivers/nvmem/apple-efuses.c @@ -0,0 +1,81 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Apple SoC eFuse driver + * + * Copyright (C) The Asahi Linux Contributors + */ + +#include +#include +#include +#include + +struct apple_efuses_priv { + void __iomem *fuses; +}; + +static int apple_efuses_read(void *context, unsigned int offset, void *val, + size_t bytes) +{ + struct apple_efuses_priv *priv = context; + u32 *dst = val; + + while (bytes >= sizeof(u32)) { + *dst++ = readl_relaxed(priv->fuses + offset); + bytes -= sizeof(u32); + offset += sizeof(u32); + } + + return 0; +} + +static int apple_efuses_probe(struct platform_device *pdev) +{ + struct apple_efuses_priv *priv; + struct resource *res; + struct nvmem_config config = { + .dev = &pdev->dev, + .add_legacy_fixed_of_cells = true, + .read_only = true, + .reg_read = apple_efuses_read, + .stride = sizeof(u32), + .word_size = sizeof(u32), + .name = "apple_efuses_nvmem", + .id = NVMEM_DEVID_AUTO, + .root_only = true, + }; + + priv = devm_kzalloc(config.dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->fuses = devm_platform_get_and_ioremap_resource(pdev, 0, &res); + if (IS_ERR(priv->fuses)) + return PTR_ERR(priv->fuses); + + config.priv = priv; + config.size = resource_size(res); + + return PTR_ERR_OR_ZERO(devm_nvmem_register(config.dev, &config)); +} + +static const struct of_device_id apple_efuses_of_match[] = { + { .compatible = "apple,efuses", }, + {} +}; + +MODULE_DEVICE_TABLE(of, apple_efuses_of_match); + +static struct platform_driver apple_efuses_driver = { + .driver = { + .name = "apple_efuses", + .of_match_table = apple_efuses_of_match, + }, + .probe = apple_efuses_probe, +}; + +module_platform_driver(apple_efuses_driver); + +MODULE_AUTHOR("Sven Peter "); +MODULE_DESCRIPTION("Apple SoC eFuse driver"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1