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/boot/bootp.c | 214 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 214 insertions(+) create mode 100644 arch/alpha/boot/bootp.c (limited to 'arch/alpha/boot/bootp.c') diff --git a/arch/alpha/boot/bootp.c b/arch/alpha/boot/bootp.c new file mode 100644 index 000000000..842e85776 --- /dev/null +++ b/arch/alpha/boot/bootp.c @@ -0,0 +1,214 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * arch/alpha/boot/bootp.c + * + * Copyright (C) 1997 Jay Estabrook + * + * This file is used for creating a bootp file for the Linux/AXP kernel + * + * based significantly on the arch/alpha/boot/main.c of Linus Torvalds + */ +#include +#include +#include +#include +#include + +#include +#include +#include + +#include + +#include "ksize.h" + +extern unsigned long switch_to_osf_pal(unsigned long nr, + struct pcb_struct *pcb_va, struct pcb_struct *pcb_pa, + unsigned long *vptb); + +extern void move_stack(unsigned long new_stack); + +struct hwrpb_struct *hwrpb = INIT_HWRPB; +static struct pcb_struct pcb_va[1]; + +/* + * Find a physical address of a virtual object.. + * + * This is easy using the virtual page table address. + */ + +static inline void * +find_pa(unsigned long *vptb, void *ptr) +{ + unsigned long address = (unsigned long) ptr; + unsigned long result; + + result = vptb[address >> 13]; + result >>= 32; + result <<= 13; + result |= address & 0x1fff; + return (void *) result; +} + +/* + * This function moves into OSF/1 pal-code, and has a temporary + * PCB for that. The kernel proper should replace this PCB with + * the real one as soon as possible. + * + * The page table muckery in here depends on the fact that the boot + * code has the L1 page table identity-map itself in the second PTE + * in the L1 page table. Thus the L1-page is virtually addressable + * itself (through three levels) at virtual address 0x200802000. + */ + +#define VPTB ((unsigned long *) 0x200000000) +#define L1 ((unsigned long *) 0x200802000) + +void +pal_init(void) +{ + unsigned long i, rev; + struct percpu_struct * percpu; + struct pcb_struct * pcb_pa; + + /* Create the dummy PCB. */ + pcb_va->ksp = 0; + pcb_va->usp = 0; + pcb_va->ptbr = L1[1] >> 32; + pcb_va->asn = 0; + pcb_va->pcc = 0; + pcb_va->unique = 0; + pcb_va->flags = 1; + pcb_va->res1 = 0; + pcb_va->res2 = 0; + pcb_pa = find_pa(VPTB, pcb_va); + + /* + * a0 = 2 (OSF) + * a1 = return address, but we give the asm the vaddr of the PCB + * a2 = physical addr of PCB + * a3 = new virtual page table pointer + * a4 = KSP (but the asm sets it) + */ + srm_printk("Switching to OSF PAL-code .. "); + + i = switch_to_osf_pal(2, pcb_va, pcb_pa, VPTB); + if (i) { + srm_printk("failed, code %ld\n", i); + __halt(); + } + + percpu = (struct percpu_struct *) + (INIT_HWRPB->processor_offset + (unsigned long) INIT_HWRPB); + rev = percpu->pal_revision = percpu->palcode_avail[2]; + + srm_printk("Ok (rev %lx)\n", rev); + + tbia(); /* do it directly in case we are SMP */ +} + +static inline void +load(unsigned long dst, unsigned long src, unsigned long count) +{ + memcpy((void *)dst, (void *)src, count); +} + +/* + * Start the kernel. + */ +static inline void +runkernel(void) +{ + __asm__ __volatile__( + "bis %0,%0,$27\n\t" + "jmp ($27)" + : /* no outputs: it doesn't even return */ + : "r" (START_ADDR)); +} + +extern char _end; +#define KERNEL_ORIGIN \ + ((((unsigned long)&_end) + 511) & ~511) + +void +start_kernel(void) +{ + /* + * Note that this crufty stuff with static and envval + * and envbuf is because: + * + * 1. Frequently, the stack is short, and we don't want to overrun; + * 2. Frequently the stack is where we are going to copy the kernel to; + * 3. A certain SRM console required the GET_ENV output to stack. + * ??? A comment in the aboot sources indicates that the GET_ENV + * destination must be quadword aligned. Might this explain the + * behaviour, rather than requiring output to the stack, which + * seems rather far-fetched. + */ + static long nbytes; + static char envval[256] __attribute__((aligned(8))); + static unsigned long initrd_start; + + srm_printk("Linux/AXP bootp loader for Linux " UTS_RELEASE "\n"); + if (INIT_HWRPB->pagesize != 8192) { + srm_printk("Expected 8kB pages, got %ldkB\n", + INIT_HWRPB->pagesize >> 10); + return; + } + if (INIT_HWRPB->vptb != (unsigned long) VPTB) { + srm_printk("Expected vptb at %p, got %p\n", + VPTB, (void *)INIT_HWRPB->vptb); + return; + } + pal_init(); + + /* The initrd must be page-aligned. See below for the + cause of the magic number 5. */ + initrd_start = ((START_ADDR + 5*KERNEL_SIZE + PAGE_SIZE) | + (PAGE_SIZE-1)) + 1; +#ifdef INITRD_IMAGE_SIZE + srm_printk("Initrd positioned at %#lx\n", initrd_start); +#endif + + /* + * Move the stack to a safe place to ensure it won't be + * overwritten by kernel image. + */ + move_stack(initrd_start - PAGE_SIZE); + + nbytes = callback_getenv(ENV_BOOTED_OSFLAGS, envval, sizeof(envval)); + if (nbytes < 0 || nbytes >= sizeof(envval)) { + nbytes = 0; + } + envval[nbytes] = '\0'; + srm_printk("Loading the kernel...'%s'\n", envval); + + /* NOTE: *no* callbacks or printouts from here on out!!! */ + + /* This is a hack, as some consoles seem to get virtual 20000000 (ie + * where the SRM console puts the kernel bootp image) memory + * overlapping physical memory where the kernel wants to be put, + * which causes real problems when attempting to copy the former to + * the latter... :-( + * + * So, we first move the kernel virtual-to-physical way above where + * we physically want the kernel to end up, then copy it from there + * to its final resting place... ;-} + * + * Sigh... */ + +#ifdef INITRD_IMAGE_SIZE + load(initrd_start, KERNEL_ORIGIN+KERNEL_SIZE, INITRD_IMAGE_SIZE); +#endif + load(START_ADDR+(4*KERNEL_SIZE), KERNEL_ORIGIN, KERNEL_SIZE); + load(START_ADDR, START_ADDR+(4*KERNEL_SIZE), KERNEL_SIZE); + + memset((char*)ZERO_PGE, 0, PAGE_SIZE); + strcpy((char*)ZERO_PGE, envval); +#ifdef INITRD_IMAGE_SIZE + ((long *)(ZERO_PGE+256))[0] = initrd_start; + ((long *)(ZERO_PGE+256))[1] = INITRD_IMAGE_SIZE; +#endif + + runkernel(); +} -- cgit v1.3.1