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

[Ashish Kalra]

From: Ashish Kalra <ashish.ka...@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.ka...@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