linux-kernel - [PATCH v5 14/14] KVM: x86: Add kexec support for SEV Live Migration.

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Message-Id: <a823eb9c85b47bcd0a1447a50af968b3e2ae92fb.1585531159.git.ashish.kalra@amd.com>
Date:   Mon, 30 Mar 2020 01:38:12 +0000
From:   Ashish Kalra <Ashish.Kalra@....com>
To:     pbonzini@...hat.com
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        joro@...tes.org, bp@...e.de, thomas.lendacky@....com,
        x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        rientjes@...gle.com, srutherford@...gle.com, luto@...nel.org,
        brijesh.singh@....com
Subject: [PATCH v5 14/14] KVM: x86: Add kexec support for SEV Live Migration.

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

Signed-off-by: Ashish Kalra <ashish.kalra@....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 8fcee0b45231..ba6cce3c84af 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -34,6 +34,7 @@
 #include <asm/hypervisor.h>
 #include <asm/tlb.h>
 #include <asm/cpuidle_haltpoll.h>
+#include <asm/e820/api.h>
 
 static int kvmapf = 1;
 
@@ -357,6 +358,33 @@ 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 (kvm_para_has_feature(KVM_FEATURE_SEV_LIVE_MIGRATION) &&
+		(smp_processor_id() == 0)) {
+		unsigned long nr_pages;
+		int i;
+
+		for (i = 0; i < e820_table->nr_entries; i++) {
+			struct e820_entry *entry = &e820_table->entries[i];
+			unsigned long start_pfn, 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