From: Ashish Kalra <ashish.kalra@amd.com>
Date: Tue, 24 Aug 2021 11:07:07 +0000
Subject: x86/kvm: Add guest support for detecting and enabling SEV Live
Migration feature.
Git-commit: f4495615d76cfe5a633b0886b5c30310ed94c357
Patch-mainline: v5.16-rc1
References: bsc#1194316
The guest support for detecting and enabling SEV Live migration
feature uses the following logic :
- kvm_init_plaform() checks if its booted under the EFI
- If not EFI,
i) if kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL), issue a wrmsrl()
to enable the SEV live migration support
- If EFI,
i) If kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL), read
the UEFI variable which indicates OVMF support for live migration
ii) the variable indicates live migration is supported, issue a wrmsrl() to
enable the SEV live migration support
The EFI live migration check is done using a late_initcall() callback.
Also, ensure that _bss_decrypted section is marked as decrypted in the
hypervisor's guest page encryption status tracking.
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Reviewed-by: Steve Rutherford <srutherford@google.com>
Message-Id: <b4453e4c87103ebef12217d2505ea99a1c3e0f0f.1629726117.git.ashish.kalra@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
arch/x86/include/asm/mem_encrypt.h | 4 +
arch/x86/kernel/kvm.c | 82 +++++++++++++++++++++++++++++++++++++
arch/x86/mm/mem_encrypt.c | 5 ++
3 files changed, 91 insertions(+)
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -44,6 +44,8 @@ void __init sme_enable(struct boot_param
int __init early_set_memory_decrypted(unsigned long vaddr, unsigned long size);
int __init early_set_memory_encrypted(unsigned long vaddr, unsigned long size);
+void __init early_set_mem_enc_dec_hypercall(unsigned long vaddr, int npages,
+ bool enc);
void __init mem_encrypt_free_decrypted_mem(void);
@@ -78,6 +80,8 @@ static inline int __init
early_set_memory_decrypted(unsigned long vaddr, unsigned long size) { return 0; }
static inline int __init
early_set_memory_encrypted(unsigned long vaddr, unsigned long size) { return 0; }
+static inline void __init
+early_set_mem_enc_dec_hypercall(unsigned long vaddr, int npages, bool enc) {}
static inline void mem_encrypt_free_decrypted_mem(void) { }
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -28,6 +28,7 @@
#include <linux/swait.h>
#include <linux/syscore_ops.h>
#include <linux/cc_platform.h>
+#include <linux/efi.h>
#include <asm/timer.h>
#include <asm/cpu.h>
#include <asm/traps.h>
@@ -41,6 +42,7 @@
#include <asm/ptrace.h>
#include <asm/reboot.h>
#include <asm/svm.h>
+#include <asm/e820/api.h>
DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled);
@@ -434,6 +436,8 @@ static void kvm_guest_cpu_offline(bool s
kvm_disable_steal_time();
if (kvm_para_has_feature(KVM_FEATURE_PV_EOI))
wrmsrl(MSR_KVM_PV_EOI_EN, 0);
+ if (kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
+ wrmsrl(MSR_KVM_MIGRATION_CONTROL, 0);
kvm_pv_disable_apf();
if (!shutdown)
apf_task_wake_all();
@@ -548,6 +552,55 @@ static void kvm_send_ipi_mask_allbutself
__send_ipi_mask(local_mask, vector);
}
+static int __init setup_efi_kvm_sev_migration(void)
+{
+ efi_char16_t efi_sev_live_migration_enabled[] = L"SevLiveMigrationEnabled";
+ efi_guid_t efi_variable_guid = AMD_SEV_MEM_ENCRYPT_GUID;
+ efi_status_t status;
+ unsigned long size;
+ bool enabled;
+
+ if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) ||
+ !kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL))
+ return 0;
+
+ if (!efi_enabled(EFI_BOOT))
+ return 0;
+
+ if (!efi_enabled(EFI_RUNTIME_SERVICES)) {
+ pr_info("%s : EFI runtime services are not enabled\n", __func__);
+ return 0;
+ }
+
+ size = sizeof(enabled);
+
+ /* Get variable contents into buffer */
+ status = efi.get_variable(efi_sev_live_migration_enabled,
+ &efi_variable_guid, NULL, &size, &enabled);
+
+ if (status == EFI_NOT_FOUND) {
+ pr_info("%s : EFI live migration variable not found\n", __func__);
+ return 0;
+ }
+
+ if (status != EFI_SUCCESS) {
+ pr_info("%s : EFI variable retrieval failed\n", __func__);
+ return 0;
+ }
+
+ if (enabled == 0) {
+ pr_info("%s: live migration disabled in EFI\n", __func__);
+ return 0;
+ }
+
+ pr_info("%s : live migration enabled in EFI\n", __func__);
+ wrmsrl(MSR_KVM_MIGRATION_CONTROL, KVM_MIGRATION_READY);
+
+ return 1;
+}
+
+late_initcall(setup_efi_kvm_sev_migration);
+
/*
* Set the IPI entry points
*/
@@ -806,8 +859,37 @@ static bool __init kvm_msi_ext_dest_id(v
return kvm_para_has_feature(KVM_FEATURE_MSI_EXT_DEST_ID);
}
+static void kvm_sev_hc_page_enc_status(unsigned long pfn, int npages, bool enc)
+{
+ kvm_sev_hypercall3(KVM_HC_MAP_GPA_RANGE, pfn << PAGE_SHIFT, npages,
+ KVM_MAP_GPA_RANGE_ENC_STAT(enc) | KVM_MAP_GPA_RANGE_PAGE_SZ_4K);
+}
+
static void __init kvm_init_platform(void)
{
+ if (cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT) &&
+ kvm_para_has_feature(KVM_FEATURE_MIGRATION_CONTROL)) {
+ unsigned long nr_pages;
+
+ pv_ops.mmu.notify_page_enc_status_changed =
+ kvm_sev_hc_page_enc_status;
+
+ /*
+ * Ensure that _bss_decrypted section is marked as decrypted in the
+ * shared pages list.
+ */
+ nr_pages = DIV_ROUND_UP(__end_bss_decrypted - __start_bss_decrypted,
+ PAGE_SIZE);
+ early_set_mem_enc_dec_hypercall((unsigned long)__start_bss_decrypted,
+ nr_pages, 0);
+
+ /*
+ * If not booted using EFI, enable Live migration support.
+ */
+ if (!efi_enabled(EFI_BOOT))
+ wrmsrl(MSR_KVM_MIGRATION_CONTROL,
+ KVM_MIGRATION_READY);
+ }
kvmclock_init();
x86_platform.apic_post_init = kvm_apic_init;
}
--- a/arch/x86/mm/mem_encrypt.c
+++ b/arch/x86/mm/mem_encrypt.c
@@ -410,6 +410,11 @@ int __init early_set_memory_encrypted(un
return early_set_memory_enc_dec(vaddr, size, true);
}
+void __init early_set_mem_enc_dec_hypercall(unsigned long vaddr, int npages, bool enc)
+{
+ notify_range_enc_status_changed(vaddr, npages, enc);
+}
+
/* Override for DMA direct allocation check - ARCH_HAS_FORCE_DMA_UNENCRYPTED */
bool force_dma_unencrypted(struct device *dev)
{