[PATCH v8 17/18] KVM: x86: Add kexec support for SEV Live Migration.

Ashish Kalra
2020-05-05T21:21:59Z

From: Ashish Kalra <ashish.kalra@amd.com>

Reset the host's page encryption bitmap related to kernel
specific page encryption status settings before we load a
new kernel by kexec. We cannot reset the complete
page encryption bitmap here as we need to retain the
UEFI/OVMF firmware specific settings.

The host's page encryption bitmap is maintained for the
guest to keep the encrypted/decrypted state of the guest pages,
therefore we need to explicitly mark all shared pages as
encrypted again before rebooting into the new guest kernel.

Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
arch/x86/kernel/kvm.c | 28 ++++++++++++++++++++++++++++
1 file changed, 28 insertions(+)

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 4b29815de873..a8bc30d5b15b 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -35,6 +35,7 @@
#include <asm/hypervisor.h>
#include <asm/tlb.h>
#include <asm/cpuidle_haltpoll.h>
+#include <asm/e820/api.h>

static int kvmapf = 1;

@@ -358,6 +359,33 @@ static void kvm_pv_guest_cpu_reboot(void *unused)
*/
if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
wrmsrl(MSR_KVM_PV_EOI_EN, 0);
+ /*
+ * Reset the host's page encryption bitmap related to kernel
+ * specific page encryption status settings before we load a
+ * new kernel by kexec. NOTE: We cannot reset the complete
+ * page encryption bitmap here as we need to retain the
+ * UEFI/OVMF firmware specific settings.
+ */
+ if (sev_live_migration_enabled() & (smp_processor_id() == 0)) {
+ int i;
+ unsigned long nr_pages;
+
+ for (i = 0; i < e820_table->nr_entries; i++) {
+ struct e820_entry *entry = &e820_table->entries[i];
+ unsigned long start_pfn;
+ unsigned long end_pfn;
+
+ if (entry->type != E820_TYPE_RAM)
+ continue;
+
+ start_pfn = entry->addr >> PAGE_SHIFT;
+ end_pfn = (entry->addr + entry->size) >> PAGE_SHIFT;
+ nr_pages = DIV_ROUND_UP(entry->size, PAGE_SIZE);
+
+ kvm_sev_hypercall3(KVM_HC_PAGE_ENC_STATUS,
+ entry->addr, nr_pages, 1);
+ }
+ }
kvm_pv_disable_apf();
kvm_disable_steal_time();
}
--
2.17.1