From: Joerg Roedel jroedel@suse.de
GHCB protocol version 2 adds the MSR-based AP-reset-hold VMGEXIT which does not need a GHCB. Use that to park APs in 16-bit protected mode on the AP jump table.
Signed-off-by: Joerg Roedel jroedel@suse.de Signed-off-by: Vasant Karasulli vkarasulli@suse.de --- arch/x86/include/asm/realmode.h | 3 ++ arch/x86/kernel/sev.c | 55 ++++++++++++++++++--- arch/x86/realmode/rm/Makefile | 11 +++-- arch/x86/realmode/rm/header.S | 3 ++ arch/x86/realmode/rm/sev.S | 85 +++++++++++++++++++++++++++++++++ 5 files changed, 146 insertions(+), 11 deletions(-) create mode 100644 arch/x86/realmode/rm/sev.S
diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h index bd54a48fe077..b0a2aa9b8366 100644 --- a/arch/x86/include/asm/realmode.h +++ b/arch/x86/include/asm/realmode.h @@ -23,6 +23,9 @@ struct real_mode_header { u32 trampoline_header; #ifdef CONFIG_AMD_MEM_ENCRYPT u32 sev_es_trampoline_start; + u32 sev_ap_park; + u32 sev_ap_park_seg; + u32 sev_ap_park_gdt; #endif #ifdef CONFIG_X86_64 u32 trampoline_start64; diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index aa114a4f3dfc..08bf897361b9 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -33,6 +33,7 @@ #include <asm/fpu/xcr.h> #include <asm/processor.h> #include <asm/realmode.h> +#include <asm/tlbflush.h> #include <asm/setup.h> #include <asm/traps.h> #include <asm/svm.h> @@ -1140,8 +1141,9 @@ void __init snp_set_wakeup_secondary_cpu(void) void __init sev_es_setup_ap_jump_table_data(void *base, u32 pa) { struct sev_ap_jump_table_header *header; + u64 *ap_jumptable_gdt, *sev_ap_park_gdt; struct desc_ptr *gdt_descr; - u64 *ap_jumptable_gdt; + int idx;
header = base;
@@ -1151,9 +1153,16 @@ void __init sev_es_setup_ap_jump_table_data(void *base, u32 pa) * real-mode. */ ap_jumptable_gdt = (u64 *)(base + header->ap_jumptable_gdt); - ap_jumptable_gdt[SEV_APJT_CS16 / 8] = GDT_ENTRY(0x9b, pa, 0xffff); - ap_jumptable_gdt[SEV_APJT_DS16 / 8] = GDT_ENTRY(0x93, pa, 0xffff); - ap_jumptable_gdt[SEV_RM_DS / 8] = GDT_ENTRY(0x93, 0, 0xffff); + sev_ap_park_gdt = __va(real_mode_header->sev_ap_park_gdt); + + idx = SEV_APJT_CS16 / 8; + ap_jumptable_gdt[idx] = sev_ap_park_gdt[idx] = GDT_ENTRY(0x9b, pa, 0xffff); + + idx = SEV_APJT_DS16 / 8; + ap_jumptable_gdt[idx] = sev_ap_park_gdt[idx] = GDT_ENTRY(0x93, pa, 0xffff); + + idx = SEV_RM_DS / 8; + ap_jumptable_gdt[idx] = GDT_ENTRY(0x93, 0x0, 0xffff);
/* Write correct GDT base address into GDT descriptor */ gdt_descr = (struct desc_ptr *)(base + header->ap_jumptable_gdt); @@ -1342,6 +1351,38 @@ void setup_ghcb(void) }
#ifdef CONFIG_HOTPLUG_CPU +void __noreturn sev_jumptable_ap_park(void) +{ + local_irq_disable(); + + write_cr3(real_mode_header->trampoline_pgd); + + /* Exiting long mode will fail if CR4.PCIDE is set. */ + if (cpu_feature_enabled(X86_FEATURE_PCID)) + cr4_clear_bits(X86_CR4_PCIDE); + + /* + * Set all GPRs except EAX, EBX, ECX, and EDX to reset state to prepare + * for software reset. + */ + asm volatile("xorl %%r15d, %%r15d\n" + "xorl %%r14d, %%r14d\n" + "xorl %%r13d, %%r13d\n" + "xorl %%r12d, %%r12d\n" + "xorl %%r11d, %%r11d\n" + "xorl %%r10d, %%r10d\n" + "xorl %%r9d, %%r9d\n" + "xorl %%r8d, %%r8d\n" + "xorl %%esi, %%esi\n" + "xorl %%edi, %%edi\n" + "xorl %%esp, %%esp\n" + "xorl %%ebp, %%ebp\n" + "ljmpl *%0" : : + "m" (real_mode_header->sev_ap_park)); + unreachable(); +} +STACK_FRAME_NON_STANDARD(sev_jumptable_ap_park); + static void sev_es_ap_hlt_loop(void) { struct ghcb_state state; @@ -1378,8 +1419,10 @@ static void sev_es_play_dead(void) play_dead_common();
/* IRQs now disabled */ - - sev_es_ap_hlt_loop(); + if (sev_ap_jumptable_blob_installed) + sev_jumptable_ap_park(); + else + sev_es_ap_hlt_loop();
/* * If we get here, the VCPU was woken up again. Jump to CPU diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile index f614009d3e4e..7fa22159f7d8 100644 --- a/arch/x86/realmode/rm/Makefile +++ b/arch/x86/realmode/rm/Makefile @@ -28,11 +28,12 @@ wakeup-objs += video-vga.o wakeup-objs += video-vesa.o wakeup-objs += video-bios.o
-realmode-y += header.o -realmode-y += trampoline_$(BITS).o -realmode-y += stack.o -realmode-y += reboot.o -realmode-$(CONFIG_ACPI_SLEEP) += $(wakeup-objs) +realmode-y += header.o +realmode-y += trampoline_$(BITS).o +realmode-y += stack.o +realmode-y += reboot.o +realmode-$(CONFIG_ACPI_SLEEP) += $(wakeup-objs) +realmode-$(CONFIG_AMD_MEM_ENCRYPT) += sev.o
targets += $(realmode-y)
diff --git a/arch/x86/realmode/rm/header.S b/arch/x86/realmode/rm/header.S index 2eb62be6d256..17eae256d443 100644 --- a/arch/x86/realmode/rm/header.S +++ b/arch/x86/realmode/rm/header.S @@ -22,6 +22,9 @@ SYM_DATA_START(real_mode_header) .long pa_trampoline_header #ifdef CONFIG_AMD_MEM_ENCRYPT .long pa_sev_es_trampoline_start + .long pa_sev_ap_park_asm + .long __KERNEL32_CS + .long pa_sev_ap_park_gdt; #endif #ifdef CONFIG_X86_64 .long pa_trampoline_start64 diff --git a/arch/x86/realmode/rm/sev.S b/arch/x86/realmode/rm/sev.S new file mode 100644 index 000000000000..ae6eea2d53f7 --- /dev/null +++ b/arch/x86/realmode/rm/sev.S @@ -0,0 +1,85 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include <linux/linkage.h> +#include <asm/segment.h> +#include <asm/page_types.h> +#include <asm/processor-flags.h> +#include <asm/msr-index.h> +#include <asm/sev-ap-jumptable.h> +#include "realmode.h" + + .section ".text32", "ax" + .code32 +/* + * The following code switches to 16-bit protected mode and sets up the + * execution environment for the AP jump table blob. Then it jumps to the AP + * jump table to park the AP. + * + * The code was copied from reboot.S and modified to fit the SEV-ES requirements + * for AP parking. When this code is entered, all registers except %EAX-%EDX are + * in reset state. + * + * %EAX, %EBX, %ECX, %EDX and EFLAGS are undefined. Only use registers %EAX-%EDX and + * %ESP in this code. + */ +SYM_CODE_START(sev_ap_park_asm) + + /* Switch to trampoline GDT as it is guaranteed < 4 GiB */ + movl $__KERNEL_DS, %eax + movl %eax, %ds + lgdt pa_tr_gdt + + /* Disable paging to drop us out of long mode */ + movl %cr0, %eax + btcl $X86_CR0_PG_BIT, %eax + movl %eax, %cr0 + + ljmpl $__KERNEL32_CS, $pa_sev_ap_park_paging_off + +SYM_INNER_LABEL(sev_ap_park_paging_off, SYM_L_GLOBAL) + /* Clear EFER */ + xorl %eax, %eax + xorl %edx, %edx + movl $MSR_EFER, %ecx + wrmsr + + /* Clear CR3 */ + xorl %ecx, %ecx + movl %ecx, %cr3 + + /* Set up the IDT for real mode. */ + lidtl pa_machine_real_restart_idt + + /* Load the GDT with the 16-bit segments for the AP jump table */ + lgdtl pa_sev_ap_park_gdt + + /* Setup code and data segments for AP jump table */ + movw $SEV_APJT_DS16, %ax + movw %ax, %ds + movw %ax, %ss + + /* Jump to the AP jump table into 16 bit protected mode */ + ljmpw $SEV_APJT_CS16, $SEV_APJT_ENTRY +SYM_CODE_END(sev_ap_park_asm) + + .data + .balign 16 +SYM_DATA_START(sev_ap_park_gdt) + /* Self-pointer */ + .word sev_ap_park_gdt_end - sev_ap_park_gdt - 1 + .long pa_sev_ap_park_gdt + .word 0 + + /* + * Offset 0x8 + * 32 bit code segment descriptor pointing to AP jump table base + * Setup at runtime in sev_es_setup_ap_jump_table_data(). + */ + .quad 0 + + /* + * Offset 0x10 + * 32 bit data segment descriptor pointing to AP jump table base + * Setup at runtime in sev_es_setup_ap_jump_table_data(). + */ + .quad 0 +SYM_DATA_END_LABEL(sev_ap_park_gdt, SYM_L_GLOBAL, sev_ap_park_gdt_end) -- 2.34.1