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 --- arch/powerpc/lib/pmem.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 arch/powerpc/lib/pmem.c (limited to 'arch/powerpc/lib/pmem.c') diff --git a/arch/powerpc/lib/pmem.c b/arch/powerpc/lib/pmem.c new file mode 100644 index 000000000..0f0f2d851 --- /dev/null +++ b/arch/powerpc/lib/pmem.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright(c) 2017 IBM Corporation. All rights reserved. + */ + +#include +#include +#include +#include + +#include + +static inline void __clean_pmem_range(unsigned long start, unsigned long stop) +{ + unsigned long shift = l1_dcache_shift(); + unsigned long bytes = l1_dcache_bytes(); + void *addr = (void *)(start & ~(bytes - 1)); + unsigned long size = stop - (unsigned long)addr + (bytes - 1); + unsigned long i; + + for (i = 0; i < size >> shift; i++, addr += bytes) + asm volatile(PPC_DCBSTPS(%0, %1): :"i"(0), "r"(addr): "memory"); +} + +static inline void __flush_pmem_range(unsigned long start, unsigned long stop) +{ + unsigned long shift = l1_dcache_shift(); + unsigned long bytes = l1_dcache_bytes(); + void *addr = (void *)(start & ~(bytes - 1)); + unsigned long size = stop - (unsigned long)addr + (bytes - 1); + unsigned long i; + + for (i = 0; i < size >> shift; i++, addr += bytes) + asm volatile(PPC_DCBFPS(%0, %1): :"i"(0), "r"(addr): "memory"); +} + +static inline void clean_pmem_range(unsigned long start, unsigned long stop) +{ + if (cpu_has_feature(CPU_FTR_ARCH_207S)) + return __clean_pmem_range(start, stop); +} + +static inline void flush_pmem_range(unsigned long start, unsigned long stop) +{ + if (cpu_has_feature(CPU_FTR_ARCH_207S)) + return __flush_pmem_range(start, stop); +} + +/* + * CONFIG_ARCH_HAS_PMEM_API symbols + */ +void arch_wb_cache_pmem(void *addr, size_t size) +{ + unsigned long start = (unsigned long) addr; + clean_pmem_range(start, start + size); +} +EXPORT_SYMBOL_GPL(arch_wb_cache_pmem); + +void arch_invalidate_pmem(void *addr, size_t size) +{ + unsigned long start = (unsigned long) addr; + flush_pmem_range(start, start + size); +} +EXPORT_SYMBOL_GPL(arch_invalidate_pmem); + +/* + * CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE symbols + */ +size_t copy_from_user_flushcache(void *dest, const void __user *src, + size_t size) +{ + unsigned long not_copied, start = (unsigned long) dest; + + src = mask_user_address(src); + not_copied = __copy_from_user(dest, src, size); + clean_pmem_range(start, start + size); + + return not_copied; +} + +void memcpy_flushcache(void *dest, const void *src, size_t size) +{ + unsigned long start = (unsigned long) dest; + + memcpy(dest, src, size); + clean_pmem_range(start, start + size); +} +EXPORT_SYMBOL(memcpy_flushcache); -- cgit v1.3.1