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/head.S | 124 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100644 arch/alpha/boot/head.S (limited to 'arch/alpha/boot/head.S') diff --git a/arch/alpha/boot/head.S b/arch/alpha/boot/head.S new file mode 100644 index 000000000..06a7c95fe --- /dev/null +++ b/arch/alpha/boot/head.S @@ -0,0 +1,124 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * arch/alpha/boot/head.S + * + * initial bootloader stuff.. + */ + +#include + + .set noreorder + .globl __start + .ent __start +__start: + br $29,2f +2: ldgp $29,0($29) + jsr $26,start_kernel + call_pal PAL_halt + .end __start + + .align 5 + .globl wrent + .ent wrent +wrent: + .prologue 0 + call_pal PAL_wrent + ret ($26) + .end wrent + + .align 5 + .globl wrkgp + .ent wrkgp +wrkgp: + .prologue 0 + call_pal PAL_wrkgp + ret ($26) + .end wrkgp + + .align 5 + .globl switch_to_osf_pal + .ent switch_to_osf_pal +switch_to_osf_pal: + subq $30,128,$30 + .frame $30,128,$26 + stq $26,0($30) + stq $1,8($30) + stq $2,16($30) + stq $3,24($30) + stq $4,32($30) + stq $5,40($30) + stq $6,48($30) + stq $7,56($30) + stq $8,64($30) + stq $9,72($30) + stq $10,80($30) + stq $11,88($30) + stq $12,96($30) + stq $13,104($30) + stq $14,112($30) + stq $15,120($30) + .prologue 0 + + stq $30,0($17) /* save KSP in PCB */ + + bis $30,$30,$20 /* a4 = KSP */ + br $17,1f + + ldq $26,0($30) + ldq $1,8($30) + ldq $2,16($30) + ldq $3,24($30) + ldq $4,32($30) + ldq $5,40($30) + ldq $6,48($30) + ldq $7,56($30) + ldq $8,64($30) + ldq $9,72($30) + ldq $10,80($30) + ldq $11,88($30) + ldq $12,96($30) + ldq $13,104($30) + ldq $14,112($30) + ldq $15,120($30) + addq $30,128,$30 + ret ($26) +1: call_pal PAL_swppal + .end switch_to_osf_pal + + .align 3 + .globl tbi + .ent tbi +tbi: + .prologue 0 + call_pal PAL_tbi + ret ($26) + .end tbi + + .align 3 + .globl halt + .ent halt +halt: + .prologue 0 + call_pal PAL_halt + .end halt + +/* $16 - new stack page */ + .align 3 + .globl move_stack + .ent move_stack +move_stack: + .prologue 0 + lda $0, 0x1fff($31) + and $0, $30, $1 /* Stack offset */ + or $1, $16, $16 /* New stack pointer */ + mov $30, $1 + mov $16, $2 +1: ldq $3, 0($1) /* Move the stack */ + addq $1, 8, $1 + stq $3, 0($2) + and $0, $1, $4 + addq $2, 8, $2 + bne $4, 1b + mov $16, $30 + ret ($26) + .end move_stack -- cgit v1.3.1