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/hyperv/hvgdk_ext.h | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 include/hyperv/hvgdk_ext.h (limited to 'include/hyperv/hvgdk_ext.h') diff --git a/include/hyperv/hvgdk_ext.h b/include/hyperv/hvgdk_ext.h new file mode 100644 index 000000000..641b591ee --- /dev/null +++ b/include/hyperv/hvgdk_ext.h @@ -0,0 +1,46 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Type definitions for the Microsoft Hypervisor. + */ +#ifndef _HV_HVGDK_EXT_H +#define _HV_HVGDK_EXT_H + +#include "hvgdk_mini.h" + +/* Extended hypercalls */ +#define HV_EXT_CALL_QUERY_CAPABILITIES 0x8001 +#define HV_EXT_CALL_MEMORY_HEAT_HINT 0x8003 + +/* Extended hypercalls */ +enum { /* HV_EXT_CALL */ + HV_EXTCALL_QUERY_CAPABILITIES = 0x8001, + HV_EXTCALL_MEMORY_HEAT_HINT = 0x8003, +}; + +/* HV_EXT_OUTPUT_QUERY_CAPABILITIES */ +#define HV_EXT_CAPABILITY_MEMORY_COLD_DISCARD_HINT BIT(8) + +enum { /* HV_EXT_MEMORY_HEAT_HINT_TYPE */ + HV_EXTMEM_HEAT_HINT_COLD = 0, + HV_EXTMEM_HEAT_HINT_HOT = 1, + HV_EXTMEM_HEAT_HINT_COLD_DISCARD = 2, + HV_EXTMEM_HEAT_HINT_MAX +}; + +/* + * The whole argument should fit in a page to be able to pass to the hypervisor + * in one hypercall. + */ +#define HV_MEMORY_HINT_MAX_GPA_PAGE_RANGES \ + ((HV_HYP_PAGE_SIZE - sizeof(struct hv_memory_hint)) / \ + sizeof(union hv_gpa_page_range)) + +/* HvExtCallMemoryHeatHint hypercall */ +#define HV_EXT_MEMORY_HEAT_HINT_TYPE_COLD_DISCARD 2 +struct hv_memory_hint { /* HV_EXT_INPUT_MEMORY_HEAT_HINT */ + u64 heat_type : 2; /* HV_EXTMEM_HEAT_HINT_* */ + u64 reserved : 62; + union hv_gpa_page_range ranges[]; +} __packed; + +#endif /* _HV_HVGDK_EXT_H */ -- cgit v1.3.1