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/arm/lib/memcpy.S | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 66 insertions(+) create mode 100644 arch/arm/lib/memcpy.S (limited to 'arch/arm/lib/memcpy.S') diff --git a/arch/arm/lib/memcpy.S b/arch/arm/lib/memcpy.S new file mode 100644 index 000000000..90f2b645a --- /dev/null +++ b/arch/arm/lib/memcpy.S @@ -0,0 +1,66 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * linux/arch/arm/lib/memcpy.S + * + * Author: Nicolas Pitre + * Created: Sep 28, 2005 + * Copyright: MontaVista Software, Inc. + */ + +#include +#include +#include + +#define LDR1W_SHIFT 0 +#define STR1W_SHIFT 0 + + .macro ldr1w ptr reg abort + W(ldr) \reg, [\ptr], #4 + .endm + + .macro ldr4w ptr reg1 reg2 reg3 reg4 abort + ldmia \ptr!, {\reg1, \reg2, \reg3, \reg4} + .endm + + .macro ldr8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort + ldmia \ptr!, {\reg1, \reg2, \reg3, \reg4, \reg5, \reg6, \reg7, \reg8} + .endm + + .macro ldr1b ptr reg cond=al abort + ldrb\cond \reg, [\ptr], #1 + .endm + + .macro str1w ptr reg abort + W(str) \reg, [\ptr], #4 + .endm + + .macro str8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort + stmia \ptr!, {\reg1, \reg2, \reg3, \reg4, \reg5, \reg6, \reg7, \reg8} + .endm + + .macro str1b ptr reg cond=al abort + strb\cond \reg, [\ptr], #1 + .endm + + .macro enter regs:vararg +UNWIND( .save {r0, \regs} ) + stmdb sp!, {r0, \regs} + .endm + + .macro exit regs:vararg + ldmfd sp!, {r0, \regs} + .endm + + .text + +/* Prototype: void *memcpy(void *dest, const void *src, size_t n); */ + +ENTRY(__memcpy) +ENTRY(mmiocpy) +WEAK(memcpy) + +#include "copy_template.S" + +ENDPROC(memcpy) +ENDPROC(mmiocpy) +ENDPROC(__memcpy) -- cgit v1.3.1