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 --- include/asm-generic/cacheflush.h | 127 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 127 insertions(+) create mode 100644 include/asm-generic/cacheflush.h (limited to 'include/asm-generic/cacheflush.h') diff --git a/include/asm-generic/cacheflush.h b/include/asm-generic/cacheflush.h new file mode 100644 index 000000000..7ee8a179d --- /dev/null +++ b/include/asm-generic/cacheflush.h @@ -0,0 +1,127 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_GENERIC_CACHEFLUSH_H +#define _ASM_GENERIC_CACHEFLUSH_H + +#include + +struct mm_struct; +struct vm_area_struct; +struct page; +struct address_space; + +/* + * The cache doesn't need to be flushed when TLB entries change when + * the cache is mapped to physical memory, not virtual memory + */ +#ifndef flush_cache_all +static inline void flush_cache_all(void) +{ +} +#endif + +#ifndef flush_cache_mm +static inline void flush_cache_mm(struct mm_struct *mm) +{ +} +#endif + +#ifndef flush_cache_dup_mm +static inline void flush_cache_dup_mm(struct mm_struct *mm) +{ +} +#endif + +#ifndef flush_cache_range +static inline void flush_cache_range(struct vm_area_struct *vma, + unsigned long start, + unsigned long end) +{ +} +#endif + +#ifndef flush_cache_page +static inline void flush_cache_page(struct vm_area_struct *vma, + unsigned long vmaddr, + unsigned long pfn) +{ +} +#endif + +#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE +static inline void flush_dcache_page(struct page *page) +{ +} + +#define ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE 0 +#endif + +#ifndef flush_dcache_mmap_lock +static inline void flush_dcache_mmap_lock(struct address_space *mapping) +{ +} +#endif + +#ifndef flush_dcache_mmap_unlock +static inline void flush_dcache_mmap_unlock(struct address_space *mapping) +{ +} +#endif + +#ifndef flush_icache_range +static inline void flush_icache_range(unsigned long start, unsigned long end) +{ +} +#endif + +#ifndef flush_icache_user_range +#define flush_icache_user_range flush_icache_range +#endif + +#ifndef flush_icache_user_page +static inline void flush_icache_user_page(struct vm_area_struct *vma, + struct page *page, + unsigned long addr, int len) +{ +} +#endif + +#ifndef flush_cache_vmap +static inline void flush_cache_vmap(unsigned long start, unsigned long end) +{ +} +#endif + +#ifndef flush_cache_vmap_early +static inline void flush_cache_vmap_early(unsigned long start, unsigned long end) +{ +} +#endif + +#ifndef flush_cache_vunmap +static inline void flush_cache_vunmap(unsigned long start, unsigned long end) +{ +} +#endif + +#ifndef copy_to_user_page +#define copy_to_user_page(vma, page, vaddr, dst, src, len) \ + do { \ + instrument_copy_to_user((void __user *)dst, src, len); \ + memcpy(dst, src, len); \ + flush_icache_user_page(vma, page, vaddr, len); \ + } while (0) +#endif + + +#ifndef copy_from_user_page +#define copy_from_user_page(vma, page, vaddr, dst, src, len) \ + do { \ + instrument_copy_from_user_before(dst, (void __user *)src, \ + len); \ + memcpy(dst, src, len); \ + instrument_copy_from_user_after(dst, (void __user *)src, len, \ + 0); \ + } while (0) +#endif + +#endif /* _ASM_GENERIC_CACHEFLUSH_H */ -- cgit v1.3.1