From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from theia.8bytes.org (8bytes.org [81.169.241.247]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 852952F80 for ; Mon, 5 Jul 2021 08:26:24 +0000 (UTC) Received: from cap.home.8bytes.org (p5b006775.dip0.t-ipconnect.de [91.0.103.117]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by theia.8bytes.org (Postfix) with ESMTPSA id 07D7D9D9; Mon, 5 Jul 2021 10:26:17 +0200 (CEST) From: Joerg Roedel To: x86@kernel.org Cc: Joerg Roedel , Joerg Roedel , hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , David Rientjes , Cfir Cohen , Erdem Aktas , Masami Hiramatsu , Mike Stunes , Sean Christopherson , Martin Radev , Arvind Sankar , linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: [RFC PATCH 08/12] x86/sev: Park APs on AP Jump Table with GHCB protocol version 2 Date: Mon, 5 Jul 2021 10:24:39 +0200 Message-Id: <20210705082443.14721-9-joro@8bytes.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210705082443.14721-1-joro@8bytes.org> References: <20210705082443.14721-1-joro@8bytes.org> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Joerg Roedel 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 --- arch/x86/include/asm/realmode.h | 3 + arch/x86/kernel/sev.c | 48 ++++++++++++++-- arch/x86/realmode/rm/Makefile | 11 ++-- arch/x86/realmode/rm/header.S | 3 + arch/x86/realmode/rm/sev_ap_park.S | 89 ++++++++++++++++++++++++++++++ 5 files changed, 144 insertions(+), 10 deletions(-) create mode 100644 arch/x86/realmode/rm/sev_ap_park.S diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h index 29590a4ddf24..668de0a8b1ae 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_real_ap_park_asm; + u32 sev_real_ap_park_seg; + u32 sev_ap_park_gdt; #endif #ifdef CONFIG_X86_64 u32 trampoline_pgd; diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 0946ef732a62..2147ebd0e919 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #include #include @@ -695,6 +696,35 @@ static bool __init sev_es_setup_ghcb(void) } #ifdef CONFIG_HOTPLUG_CPU +static 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 (boot_cpu_has(X86_FEATURE_PCID)) + cr4_clear_bits(X86_CR4_PCIDE); + + asm volatile("xorq %%r15, %%r15\n" + "xorq %%r14, %%r14\n" + "xorq %%r13, %%r13\n" + "xorq %%r12, %%r12\n" + "xorq %%r11, %%r11\n" + "xorq %%r10, %%r10\n" + "xorq %%r9, %%r9\n" + "xorq %%r8, %%r8\n" + "xorq %%rsi, %%rsi\n" + "xorq %%rdi, %%rdi\n" + "xorq %%rsp, %%rsp\n" + "xorq %%rbp, %%rbp\n" + "ljmpl *%0" : : + "m" (real_mode_header->sev_real_ap_park_asm), + "b" (sev_es_jump_table_pa >> 4)); + unreachable(); +} +STACK_FRAME_NON_STANDARD(sev_jumptable_ap_park); + static void sev_es_ap_hlt_loop(void) { struct ghcb_state state; @@ -731,8 +761,10 @@ 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 @@ -762,8 +794,9 @@ static inline void sev_es_setup_play_dead(void) { } static 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; @@ -773,8 +806,13 @@ static void __init sev_es_setup_ap_jump_table_data(void *base, u32 pa) * real-mode. */ ap_jumptable_gdt = (u64 *)(base + header->gdt_offset); - ap_jumptable_gdt[SEV_APJT_CS16 / 8] = GDT_ENTRY(0x9b, pa, 0xffff); - ap_jumptable_gdt[SEV_APJT_DS16 / 8] = GDT_ENTRY(0x93, pa, 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); /* Write correct GDT base address into GDT descriptor */ gdt_descr = (struct desc_ptr *)(base + header->gdt_offset); diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile index 83f1b6a56449..a7f84d43a0a3 100644 --- a/arch/x86/realmode/rm/Makefile +++ b/arch/x86/realmode/rm/Makefile @@ -27,11 +27,12 @@ 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_ap_park.o targets += $(realmode-y) diff --git a/arch/x86/realmode/rm/header.S b/arch/x86/realmode/rm/header.S index 8c1db5bf5d78..6c17f8fd1eb4 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_pgd; diff --git a/arch/x86/realmode/rm/sev_ap_park.S b/arch/x86/realmode/rm/sev_ap_park.S new file mode 100644 index 000000000000..0b63d0569d4d --- /dev/null +++ b/arch/x86/realmode/rm/sev_ap_park.S @@ -0,0 +1,89 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include +#include +#include +#include +#include +#include +#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. + * + * The AP Jump Table physical base address is in %EBX upon entry. + * + * %EAX, %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 */ + movl $0, %eax + movl $0, %edx + movl $MSR_EFER, %ecx + wrmsr + + /* Clear CR3 */ + movl $0, %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) -- 2.31.1