@@ -1499,6 +1499,29 @@ enum es_result savic_register_gpa(u64 gpa)
return res;
}
+enum es_result savic_unregister_gpa(u64 *gpa)
+{
+ struct ghcb_state state;
+ struct es_em_ctxt ctxt;
+ enum es_result res;
+ struct ghcb *ghcb;
+
+ guard(irqsave)();
+
+ ghcb = __sev_get_ghcb(&state);
+ vc_ghcb_invalidate(ghcb);
+
+ ghcb_set_rax(ghcb, SVM_VMGEXIT_SAVIC_SELF_GPA);
+ res = sev_es_ghcb_hv_call(ghcb, &ctxt, SVM_VMGEXIT_SAVIC,
+ SVM_VMGEXIT_SAVIC_UNREGISTER_GPA, 0);
+ if (gpa && res == ES_OK)
+ *gpa = ghcb->save.rbx;
+
+ __sev_put_ghcb(&state);
+
+ return res;
+}
+
static void snp_register_per_cpu_ghcb(void)
{
struct sev_es_runtime_data *data;
@@ -306,6 +306,7 @@ struct apic {
/* Probe, setup and smpboot functions */
int (*probe)(void);
void (*setup)(void);
+ void (*teardown)(void);
int (*acpi_madt_oem_check)(char *oem_id, char *oem_table_id);
void (*init_apic_ldr)(void);
@@ -521,6 +521,7 @@ int snp_svsm_vtpm_send_command(u8 *buffer);
void __init snp_secure_tsc_prepare(void);
void __init snp_secure_tsc_init(void);
enum es_result savic_register_gpa(u64 gpa);
+enum es_result savic_unregister_gpa(u64 *gpa);
u64 savic_ghcb_msr_read(u32 reg);
void savic_ghcb_msr_write(u32 reg, u64 value);
@@ -574,6 +575,7 @@ static inline int snp_svsm_vtpm_send_command(u8 *buffer) { return -ENODEV; }
static inline void __init snp_secure_tsc_prepare(void) { }
static inline void __init snp_secure_tsc_init(void) { }
static inline enum es_result savic_register_gpa(u64 gpa) { return ES_UNSUPPORTED; }
+static inline enum es_result savic_unregister_gpa(u64 *gpa) { return ES_UNSUPPORTED; }
static inline void savic_ghcb_msr_write(u32 reg, u64 value) { }
static inline u64 savic_ghcb_msr_read(u32 reg) { return 0; }
@@ -1169,6 +1169,9 @@ void disable_local_APIC(void)
if (!apic_accessible())
return;
+ if (apic->teardown)
+ apic->teardown();
+
apic_soft_disable();
#ifdef CONFIG_X86_32
@@ -333,6 +333,13 @@ static void init_apic_page(void)
set_reg(APIC_ID, apic_id);
}
+static void savic_teardown(void)
+{
+ /* Disable Secure AVIC */
+ native_wrmsr(MSR_AMD64_SECURE_AVIC_CONTROL, 0, 0);
+ savic_unregister_gpa(NULL);
+}
+
static void savic_setup(void)
{
void *backing_page;
@@ -419,6 +426,7 @@ static struct apic apic_x2apic_savic __ro_after_init = {
.probe = savic_probe,
.acpi_madt_oem_check = savic_acpi_madt_oem_check,
.setup = savic_setup,
+ .teardown = savic_teardown,
.dest_mode_logical = false,
Add a apic->teardown() callback to disable Secure AVIC before rebooting into the new kernel. This ensures that the new kernel does not access the old APIC backing page which was allocated by the previous kernel. Such accesses can happen if there are any APIC accesses done during guest boot before Secure AVIC driver probe is done by the new kernel (as Secure AVIC would have remained enabled in the Secure AVIC control msr). Signed-off-by: Neeraj Upadhyay <Neeraj.Upadhyay@amd.com> --- Changes since v3: - Use SVM_VMGEXIT_SAVIC_SELF_GPA in place of -1ULL in savic_unregister_gpa(). - Use guard(irqsave)() in savic_unregister_gpa(). - Misc cleanups. arch/x86/coco/sev/core.c | 23 +++++++++++++++++++++++ arch/x86/include/asm/apic.h | 1 + arch/x86/include/asm/sev.h | 2 ++ arch/x86/kernel/apic/apic.c | 3 +++ arch/x86/kernel/apic/x2apic_savic.c | 8 ++++++++ 5 files changed, 37 insertions(+)