diff mbox series

[v6,18/33] x86/fred: add a NMI entry stub for FRED

Message ID	20230327075838.5403-19-xin3.li@intel.com
State	New
Headers	Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; From: Xin Li <xin3.li@intel.com> To: linux-kernel@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, peterz@infradead.org, andrew.cooper3@citrix.com, seanjc@google.com, pbonzini@redhat.com, ravi.v.shankar@intel.com, jiangshanlai@gmail.com, shan.kang@intel.com Subject: [PATCH v6 18/33] x86/fred: add a NMI entry stub for FRED Date: Mon, 27 Mar 2023 00:58:23 -0700 Message-Id: <20230327075838.5403-19-xin3.li@intel.com> In-Reply-To: <20230327075838.5403-1-xin3.li@intel.com> References: <20230327075838.5403-1-xin3.li@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	x86: enable FRED for x86-64 \| [v6,00/33] x86: enable FRED for x86-64 [v6,01/33] x86/traps: let common_interrupt() handle IRQ_MOVE_CLEANUP_VECTOR [v6,02/33] x86/fred: make unions for the cs and ss fields in struct pt_regs [v6,03/33] x86/traps: add a system interrupt table for system interrupt dispatch [v6,04/33] x86/traps: add install_system_interrupt_handler() [v6,05/33] x86/traps: add external_interrupt() to dispatch external interrupts [v6,06/33] x86/cpufeature: add the cpu feature bit for FRED [v6,07/33] x86/opcode: add ERETU, ERETS instructions to x86-opcode-map [v6,08/33] x86/objtool: teach objtool about ERETU and ERETS [v6,09/33] x86/cpu: add X86_CR4_FRED macro [v6,10/33] x86/fred: add Kconfig option for FRED (CONFIG_X86_FRED) [v6,11/33] x86/fred: if CONFIG_X86_FRED is disabled, disable FRED support [v6,12/33] x86/cpu: add MSR numbers for FRED configuration [v6,13/33] x86/fred: header file for event types [v6,14/33] x86/fred: header file with FRED definitions [v6,15/33] x86/fred: reserve space for the FRED stack frame [v6,16/33] x86/fred: add a page fault entry stub for FRED [v6,17/33] x86/fred: add a debug fault entry stub for FRED [v6,18/33] x86/fred: add a NMI entry stub for FRED [v6,19/33] x86/fred: add a machine check entry stub for FRED [v6,20/33] x86/fred: FRED entry/exit and dispatch code [v6,21/33] x86/fred: FRED initialization code [v6,22/33] x86/fred: update MSR_IA32_FRED_RSP0 during task switch [v6,23/33] x86/fred: let ret_from_fork() jmp to fred_exit_user when FRED is enabled [v6,24/33] x86/fred: disallow the swapgs instruction when FRED is enabled [v6,25/33] x86/fred: no ESPFIX needed when FRED is enabled [v6,26/33] x86/fred: allow single-step trap and NMI when starting a new thread [v6,27/33] x86/fred: fixup fault on ERETU by jumping to fred_entrypoint_user [v6,28/33] x86/ia32: do not modify the DPL bits for a null selector [v6,29/33] x86/fred: allow FRED systems to use interrupt vectors 0x10-0x1f [v6,30/33] x86/fred: allow dynamic stack frame size [v6,31/33] x86/fred: BUG() when ERETU with %rsp not equal to that when the ring 3 event was just de… [v6,32/33] x86/fred: disable FRED by default in its early stage [v6,33/33] KVM: x86/vmx: refactor VMX_DO_EVENT_IRQOFF to generate FRED stack frames

Commit Message

Li, Xin3 March 27, 2023, 7:58 a.m. UTC

  From: "H. Peter Anvin (Intel)" <hpa@zytor.com>

On a FRED system, NMIs nest both with themselves and faults, transient
information is saved into the stack frame, and NMI unblocking only
happens when the stack frame indicates that so should happen.

Thus, the NMI entry stub for FRED is really quite small...

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Tested-by: Shan Kang <shan.kang@intel.com>
Signed-off-by: Xin Li <xin3.li@intel.com>
---
 arch/x86/include/asm/fred.h |  1 +
 arch/x86/kernel/nmi.c       | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+)

diff mbox series

Patch

diff --git a/arch/x86/include/asm/fred.h b/arch/x86/include/asm/fred.h
index 633dd9e6a68e..f928a03082af 100644
--- a/arch/x86/include/asm/fred.h
+++ b/arch/x86/include/asm/fred.h
@@ -94,6 +94,7 @@  static __always_inline unsigned long fred_event_data(struct pt_regs *regs)
 #define DEFINE_FRED_HANDLER(f) noinstr DECLARE_FRED_HANDLER(f)
 typedef DECLARE_FRED_HANDLER((*fred_handler));
 
+DECLARE_FRED_HANDLER(fred_exc_nmi);
 DECLARE_FRED_HANDLER(fred_exc_debug);
 DECLARE_FRED_HANDLER(fred_exc_page_fault);
 
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 776f4b1e395b..e7b2abe42583 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -34,6 +34,7 @@ 
 #include <asm/cache.h>
 #include <asm/nospec-branch.h>
 #include <asm/sev.h>
+#include <asm/fred.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/nmi.h>
@@ -643,6 +644,24 @@  void nmi_backtrace_stall_check(const struct cpumask *btp)
 
 #endif
 
+#ifdef CONFIG_X86_FRED
+DEFINE_FRED_HANDLER(fred_exc_nmi)
+{
+	/*
+	 * With FRED, CR2 and DR6 are pushed atomically on faults,
+	 * so we don't have to worry about saving and restoring them.
+	 * Breakpoint faults nest, so assume it is OK to leave DR7
+	 * enabled.
+	 */
+	irqentry_state_t irq_state = irqentry_nmi_enter(regs);
+
+	inc_irq_stat(__nmi_count);
+	default_do_nmi(regs);
+
+	irqentry_nmi_exit(regs, irq_state);
+}
+#endif
+
 void stop_nmi(void)
 {
 	ignore_nmis++;