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x86/sev-es: Support CPU offline/online

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Add a play_dead handler when running under SEV-ES. This is needed
because the hypervisor can't deliver an SIPI request to restart the AP.
Instead, the kernel has to issue a VMGEXIT to halt the VCPU until the
hypervisor wakes it up again.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-70-joro@8bytes.org
This commit is contained in:
Joerg Roedel 2020-09-07 15:16:10 +02:00 committed by Borislav Petkov
parent 3ecacdbd23
commit 094794f597
2 changed files with 64 additions and 0 deletions
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1
arch/x86/include/uapi/asm/svm.h
View File

@ -84,6 +84,7 @@
/* SEV-ES software-defined VMGEXIT events */
#define SVM_VMGEXIT_MMIO_READ 0x80000001
#define SVM_VMGEXIT_MMIO_WRITE 0x80000002
#define SVM_VMGEXIT_AP_HLT_LOOP 0x80000004
#define SVM_VMGEXIT_AP_JUMP_TABLE 0x80000005
#define SVM_VMGEXIT_SET_AP_JUMP_TABLE 0
#define SVM_VMGEXIT_GET_AP_JUMP_TABLE 1

63
arch/x86/kernel/sev-es.c
View File

@ -29,6 +29,8 @@
#include <asm/realmode.h>
#include <asm/traps.h>
#include <asm/svm.h>
#include <asm/smp.h>
#include <asm/cpu.h>
#define DR7_RESET_VALUE 0x400
@ -518,6 +520,65 @@ static bool __init sev_es_setup_ghcb(void)
return true;
}
#ifdef CONFIG_HOTPLUG_CPU
static void sev_es_ap_hlt_loop(void)
{
struct ghcb_state state;
struct ghcb *ghcb;
ghcb = sev_es_get_ghcb(&state);
while (true) {
vc_ghcb_invalidate(ghcb);
ghcb_set_sw_exit_code(ghcb, SVM_VMGEXIT_AP_HLT_LOOP);
ghcb_set_sw_exit_info_1(ghcb, 0);
ghcb_set_sw_exit_info_2(ghcb, 0);
sev_es_wr_ghcb_msr(__pa(ghcb));
VMGEXIT();
/* Wakeup signal? */
if (ghcb_sw_exit_info_2_is_valid(ghcb) &&
ghcb->save.sw_exit_info_2)
break;
}
sev_es_put_ghcb(&state);
}
/*
* Play_dead handler when running under SEV-ES. This is needed because
* the hypervisor can't deliver an SIPI request to restart the AP.
* Instead the kernel has to issue a VMGEXIT to halt the VCPU until the
* hypervisor wakes it up again.
*/
static void sev_es_play_dead(void)
{
play_dead_common();
/* IRQs now disabled */
sev_es_ap_hlt_loop();
/*
* If we get here, the VCPU was woken up again. Jump to CPU
* startup code to get it back online.
*/
start_cpu0();
}
#else /* CONFIG_HOTPLUG_CPU */
#define sev_es_play_dead native_play_dead
#endif /* CONFIG_HOTPLUG_CPU */
#ifdef CONFIG_SMP
static void __init sev_es_setup_play_dead(void)
{
smp_ops.play_dead = sev_es_play_dead;
}
#else
static inline void sev_es_setup_play_dead(void) { }
#endif
static void __init alloc_runtime_data(int cpu)
{
struct sev_es_runtime_data *data;
@ -566,6 +627,8 @@ void __init sev_es_init_vc_handling(void)
setup_vc_stacks(cpu);
}
sev_es_setup_play_dead();
/* Secondary CPUs use the runtime #VC handler */
initial_vc_handler = (unsigned long)safe_stack_exc_vmm_communication;
}