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From: Joerg Roedel <joro@8bytes.org>
To: x86@kernel.org, Eric Biederman <ebiederm@xmission.com>
Cc: kexec@lists.infradead.org, Joerg Roedel <jroedel@suse.de>,
	hpa@zytor.com, Andy Lutomirski <luto@kernel.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Jiri Slaby <jslaby@suse.cz>,
	Dan Williams <dan.j.williams@intel.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Juergen Gross <jgross@suse.com>,
	Kees Cook <keescook@chromium.org>,
	David Rientjes <rientjes@google.com>,
	Cfir Cohen <cfir@google.com>, Erdem Aktas <erdemaktas@google.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mike Stunes <mstunes@vmware.com>,
	Sean Christopherson <seanjc@google.com>,
	Martin Radev <martin.b.radev@gmail.com>,
	Arvind Sankar <nivedita@alum.mit.edu>,
	Joerg Roedel <joro@8bytes.org>,
	linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org
Subject: [PATCH 09/12] x86/sev: Use AP Jump Table blob to stop CPU
Date: Wed, 21 Jul 2021 16:20:12 +0200	[thread overview]
Message-ID: <20210721142015.1401-10-joro@8bytes.org> (raw)
In-Reply-To: <20210721142015.1401-1-joro@8bytes.org>

From: Joerg Roedel <jroedel@suse.de>

To support kexec under SEV-ES the APs can't be parked with HLT. Upon
wakeup the AP needs to find its way to execute at the reset vector set
by the new kernel and in real-mode.

This is what the AP Jump Table blob provides, so stop the APs the
SEV-ES way by calling the AP-reset-hold VMGEXIT from the AP Jump
Table.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 arch/x86/include/asm/sev.h |  7 +++++++
 arch/x86/kernel/process.c  |  8 ++++++++
 arch/x86/kernel/sev.c      | 11 ++++++++++-
 3 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 134a7c9d91b6..cd14b6e10f12 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -81,12 +81,19 @@ static __always_inline void sev_es_nmi_complete(void)
 		__sev_es_nmi_complete();
 }
 extern int __init sev_es_efi_map_ghcbs(pgd_t *pgd);
+void __sev_es_stop_this_cpu(void);
+static __always_inline void sev_es_stop_this_cpu(void)
+{
+	if (static_branch_unlikely(&sev_es_enable_key))
+		__sev_es_stop_this_cpu();
+}
 #else
 static inline void sev_es_ist_enter(struct pt_regs *regs) { }
 static inline void sev_es_ist_exit(void) { }
 static inline int sev_es_setup_ap_jump_table(struct real_mode_header *rmh) { return 0; }
 static inline void sev_es_nmi_complete(void) { }
 static inline int sev_es_efi_map_ghcbs(pgd_t *pgd) { return 0; }
+static inline void sev_es_stop_this_cpu(void) { }
 #endif
 
 #endif
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 1d9463e3096b..8d9b03923baa 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -43,6 +43,7 @@
 #include <asm/io_bitmap.h>
 #include <asm/proto.h>
 #include <asm/frame.h>
+#include <asm/sev.h>
 
 #include "process.h"
 
@@ -752,6 +753,13 @@ void stop_this_cpu(void *dummy)
 	if (boot_cpu_has(X86_FEATURE_SME))
 		native_wbinvd();
 	for (;;) {
+		/*
+		 * SEV-ES guests need a special stop routine to support
+		 * kexec. Try this first, if it fails the function will
+		 * return and native_halt() is used.
+		 */
+		sev_es_stop_this_cpu();
+
 		/*
 		 * Use native_halt() so that memory contents don't change
 		 * (stack usage and variables) after possibly issuing the
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 20b439986d86..bac9bb4fa54e 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -695,7 +695,6 @@ static bool __init sev_es_setup_ghcb(void)
 	return true;
 }
 
-#ifdef CONFIG_HOTPLUG_CPU
 void __noreturn sev_jumptable_ap_park(void)
 {
 	local_irq_disable();
@@ -725,6 +724,16 @@ void __noreturn sev_jumptable_ap_park(void)
 }
 STACK_FRAME_NON_STANDARD(sev_jumptable_ap_park);
 
+void __sev_es_stop_this_cpu(void)
+{
+	/* Only park in the AP Jump Table when the code has been installed */
+	if (!sev_ap_jumptable_blob_installed)
+		return;
+
+	sev_jumptable_ap_park();
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
 static void sev_es_ap_hlt_loop(void)
 {
 	struct ghcb_state state;
-- 
2.31.1


  parent reply	other threads:[~2021-07-21 14:20 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-21 14:20 [PATCH 00/12] x86/sev: KEXEC/KDUMP support for SEV-ES guests Joerg Roedel
2021-07-21 14:20 ` [PATCH 01/12] kexec: Allow architecture code to opt-out at runtime Joerg Roedel
2021-07-21 14:20 ` [PATCH 02/12] x86/kexec/64: Forbid kexec when running as an SEV-ES guest Joerg Roedel
2021-07-21 14:20 ` [PATCH 03/12] x86/sev: Save and print negotiated GHCB protocol version Joerg Roedel
2021-07-21 14:20 ` [PATCH 04/12] x86/sev: Do not hardcode " Joerg Roedel
2021-07-21 21:17   ` Tom Lendacky
2021-07-31  7:18     ` Joerg Roedel
2021-07-21 14:20 ` [PATCH 05/12] x86/sev: Use GHCB protocol version 2 if supported Joerg Roedel
2021-07-21 14:20 ` [PATCH 06/12] x86/sev: Cache AP Jump Table Address Joerg Roedel
2021-07-21 14:20 ` [PATCH 07/12] x86/sev: Setup code to park APs in the AP Jump Table Joerg Roedel
2021-07-21 14:20 ` [PATCH 08/12] x86/sev: Park APs on AP Jump Table with GHCB protocol version 2 Joerg Roedel
2021-07-21 14:20 ` Joerg Roedel [this message]
2021-07-21 14:20 ` [PATCH 10/12] x86/sev: Add MMIO handling support to boot/compressed/ code Joerg Roedel
2021-07-21 14:20 ` [PATCH 11/12] x86/sev: Handle CLFLUSH MMIO events Joerg Roedel
2021-07-30 22:42   ` Sean Christopherson
2021-07-31  7:17     ` Joerg Roedel
2021-07-21 14:20 ` [PATCH 12/12] x86/sev: Support kexec under SEV-ES with AP Jump Table blob Joerg Roedel

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