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/alpha/mm/init.c | 266 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 266 insertions(+) create mode 100644 arch/alpha/mm/init.c (limited to 'arch/alpha/mm/init.c') diff --git a/arch/alpha/mm/init.c b/arch/alpha/mm/init.c new file mode 100644 index 000000000..f4d65a60c --- /dev/null +++ b/arch/alpha/mm/init.c @@ -0,0 +1,266 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/arch/alpha/mm/init.c + * + * Copyright (C) 1995 Linus Torvalds + */ + +/* 2.3.x zone allocator, 1999 Andrea Arcangeli */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include /* max_low_pfn */ +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../kernel/proto.h" + +static struct pcb_struct original_pcb; + +pgd_t * +pgd_alloc(struct mm_struct *mm) +{ + pgd_t *ret, *init; + + ret = __pgd_alloc(mm, 0); + init = pgd_offset(&init_mm, 0UL); + if (ret) { +#ifdef CONFIG_ALPHA_LARGE_VMALLOC + memcpy (ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD, + (PTRS_PER_PGD - USER_PTRS_PER_PGD - 1)*sizeof(pgd_t)); +#else + pgd_val(ret[PTRS_PER_PGD-2]) = pgd_val(init[PTRS_PER_PGD-2]); +#endif + + /* The last PGD entry is the VPTB self-map. */ + pgd_val(ret[PTRS_PER_PGD-1]) + = pte_val(mk_pte(virt_to_page(ret), PAGE_KERNEL)); + } + return ret; +} + + +static inline unsigned long +load_PCB(struct pcb_struct *pcb) +{ + pcb->ksp = (unsigned long)current_stack_pointer; + return __reload_thread(pcb); +} + +/* Set up initial PCB, VPTB, and other such nicities. */ + +static inline void +switch_to_system_map(void) +{ + unsigned long newptbr; + unsigned long original_pcb_ptr; + + /* Initialize the kernel's page tables. Linux puts the vptb in + the last slot of the L1 page table. */ + memset(swapper_pg_dir, 0, PAGE_SIZE); + newptbr = ((unsigned long) swapper_pg_dir - PAGE_OFFSET) >> PAGE_SHIFT; + pgd_val(swapper_pg_dir[1023]) = + (newptbr << 32) | pgprot_val(PAGE_KERNEL); + + /* Set the vptb. This is often done by the bootloader, but + shouldn't be required. */ + if (hwrpb->vptb != 0xfffffffe00000000UL) { + wrvptptr(0xfffffffe00000000UL); + hwrpb->vptb = 0xfffffffe00000000UL; + hwrpb_update_checksum(hwrpb); + } + + /* Also set up the real kernel PCB while we're at it. */ + init_thread_info.pcb.ptbr = newptbr; + init_thread_info.pcb.flags = 1; /* set FEN, clear everything else */ + original_pcb_ptr = load_PCB(&init_thread_info.pcb); + tbia(); + + /* Save off the contents of the original PCB so that we can + restore the original console's page tables for a clean reboot. + + Note that the PCB is supposed to be a physical address, but + since KSEG values also happen to work, folks get confused. + Check this here. */ + + if (original_pcb_ptr < PAGE_OFFSET) { + original_pcb_ptr = (unsigned long) + phys_to_virt(original_pcb_ptr); + } + original_pcb = *(struct pcb_struct *) original_pcb_ptr; +} + +int callback_init_done; + +void * __init +callback_init(void * kernel_end) +{ + struct crb_struct * crb; + pgd_t *pgd; + p4d_t *p4d; + pud_t *pud; + pmd_t *pmd; + void *two_pages; + + /* Starting at the HWRPB, locate the CRB. */ + crb = (struct crb_struct *)((char *)hwrpb + hwrpb->crb_offset); + + if (alpha_using_srm) { + /* Tell the console whither it is to be remapped. */ + if (srm_fixup(VMALLOC_START, (unsigned long)hwrpb)) + __halt(); /* "We're boned." --Bender */ + + /* Edit the procedure descriptors for DISPATCH and FIXUP. */ + crb->dispatch_va = (struct procdesc_struct *) + (VMALLOC_START + (unsigned long)crb->dispatch_va + - crb->map[0].va); + crb->fixup_va = (struct procdesc_struct *) + (VMALLOC_START + (unsigned long)crb->fixup_va + - crb->map[0].va); + } + + switch_to_system_map(); + + /* Allocate one PGD and one PMD. In the case of SRM, we'll need + these to actually remap the console. There is an assumption + here that only one of each is needed, and this allows for 8MB. + On systems with larger consoles, additional pages will be + allocated as needed during the mapping process. + + In the case of not SRM, but not CONFIG_ALPHA_LARGE_VMALLOC, + we need to allocate the PGD we use for vmalloc before we start + forking other tasks. */ + + two_pages = (void *) + (((unsigned long)kernel_end + ~PAGE_MASK) & PAGE_MASK); + kernel_end = two_pages + 2*PAGE_SIZE; + memset(two_pages, 0, 2*PAGE_SIZE); + + pgd = pgd_offset_k(VMALLOC_START); + p4d = p4d_offset(pgd, VMALLOC_START); + pud = pud_offset(p4d, VMALLOC_START); + pud_set(pud, (pmd_t *)two_pages); + pmd = pmd_offset(pud, VMALLOC_START); + pmd_set(pmd, (pte_t *)(two_pages + PAGE_SIZE)); + + if (alpha_using_srm) { + static struct vm_struct console_remap_vm; + unsigned long nr_pages = 0; + unsigned long vaddr; + unsigned long i, j; + + /* calculate needed size */ + for (i = 0; i < crb->map_entries; ++i) + nr_pages += crb->map[i].count; + + /* register the vm area */ + console_remap_vm.flags = VM_ALLOC; + console_remap_vm.size = nr_pages << PAGE_SHIFT; + vm_area_register_early(&console_remap_vm, PAGE_SIZE); + + vaddr = (unsigned long)console_remap_vm.addr; + + /* Set up the third level PTEs and update the virtual + addresses of the CRB entries. */ + for (i = 0; i < crb->map_entries; ++i) { + unsigned long pfn = crb->map[i].pa >> PAGE_SHIFT; + crb->map[i].va = vaddr; + for (j = 0; j < crb->map[i].count; ++j) { + /* Newer consoles (especially on larger + systems) may require more pages of + PTEs. Grab additional pages as needed. */ + if (pmd != pmd_offset(pud, vaddr)) { + memset(kernel_end, 0, PAGE_SIZE); + pmd = pmd_offset(pud, vaddr); + pmd_set(pmd, (pte_t *)kernel_end); + kernel_end += PAGE_SIZE; + } + set_pte(pte_offset_kernel(pmd, vaddr), + pfn_pte(pfn, PAGE_KERNEL)); + pfn++; + vaddr += PAGE_SIZE; + } + } + } + + callback_init_done = 1; + return kernel_end; +} + +void __init arch_zone_limits_init(unsigned long *max_zone_pfn) +{ + unsigned long dma_pfn; + + dma_pfn = virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT; + max_pfn = max_low_pfn; + + max_zone_pfn[ZONE_DMA] = dma_pfn; + max_zone_pfn[ZONE_NORMAL] = max_pfn; +} + +/* + * paging_init() initializes the kernel's ZERO_PGE. + */ +void __init paging_init(void) +{ + memset(absolute_pointer(ZERO_PGE), 0, PAGE_SIZE); +} + +#if defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_SRM) +void +srm_paging_stop (void) +{ + /* Move the vptb back to where the SRM console expects it. */ + swapper_pg_dir[1] = swapper_pg_dir[1023]; + tbia(); + wrvptptr(0x200000000UL); + hwrpb->vptb = 0x200000000UL; + hwrpb_update_checksum(hwrpb); + + /* Reload the page tables that the console had in use. */ + load_PCB(&original_pcb); + tbia(); +} +#endif + +static const pgprot_t protection_map[16] = { + [VM_NONE] = _PAGE_P(_PAGE_FOE | _PAGE_FOW | + _PAGE_FOR), + [VM_READ] = _PAGE_P(_PAGE_FOE | _PAGE_FOW), + [VM_WRITE] = _PAGE_P(_PAGE_FOE), + [VM_WRITE | VM_READ] = _PAGE_P(_PAGE_FOE), + [VM_EXEC] = _PAGE_P(_PAGE_FOW | _PAGE_FOR), + [VM_EXEC | VM_READ] = _PAGE_P(_PAGE_FOW), + [VM_EXEC | VM_WRITE] = _PAGE_P(0), + [VM_EXEC | VM_WRITE | VM_READ] = _PAGE_P(0), + [VM_SHARED] = _PAGE_S(_PAGE_FOE | _PAGE_FOW | + _PAGE_FOR), + [VM_SHARED | VM_READ] = _PAGE_S(_PAGE_FOE | _PAGE_FOW), + [VM_SHARED | VM_WRITE] = _PAGE_S(_PAGE_FOE), + [VM_SHARED | VM_WRITE | VM_READ] = _PAGE_S(_PAGE_FOE), + [VM_SHARED | VM_EXEC] = _PAGE_S(_PAGE_FOW | _PAGE_FOR), + [VM_SHARED | VM_EXEC | VM_READ] = _PAGE_S(_PAGE_FOW), + [VM_SHARED | VM_EXEC | VM_WRITE] = _PAGE_S(0), + [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = _PAGE_S(0) +}; +DECLARE_VM_GET_PAGE_PROT -- cgit v1.3.1