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[PATCH v9 20/36] x86/fred: Add a NMI entry stub for FRED
- To: linux-doc@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, linux-edac@xxxxxxxxxxxxxxx, linux-hyperv@xxxxxxxxxxxxxxx, kvm@xxxxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: Xin Li <xin3.li@xxxxxxxxx>
- Date: Sun, 30 Jul 2023 23:33:01 -0700
- Cc: Jonathan Corbet <corbet@xxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>, x86@xxxxxxxxxx, "H . Peter Anvin" <hpa@xxxxxxxxx>, Andy Lutomirski <luto@xxxxxxxxxx>, Oleg Nesterov <oleg@xxxxxxxxxx>, Tony Luck <tony.luck@xxxxxxxxx>, "K . Y . Srinivasan" <kys@xxxxxxxxxxxxx>, Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>, Wei Liu <wei.liu@xxxxxxxxxx>, Dexuan Cui <decui@xxxxxxxxxxxxx>, Paolo Bonzini <pbonzini@xxxxxxxxxx>, Wanpeng Li <wanpengli@xxxxxxxxxxx>, Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>, Sean Christopherson <seanjc@xxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, Juergen Gross <jgross@xxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>, Josh Poimboeuf <jpoimboe@xxxxxxxxxx>, "Paul E . McKenney" <paulmck@xxxxxxxxxx>, Catalin Marinas <catalin.marinas@xxxxxxx>, Randy Dunlap <rdunlap@xxxxxxxxxxxxx>, Steven Rostedt <rostedt@xxxxxxxxxxx>, Kim Phillips <kim.phillips@xxxxxxx>, Xin Li <xin3.li@xxxxxxxxx>, Hyeonggon Yoo <42.hyeyoo@xxxxxxxxx>, "Liam R . Howlett" <Liam.Howlett@xxxxxxxxxx>, Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx>, "Kirill A . Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>, Suren Baghdasaryan <surenb@xxxxxxxxxx>, Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>, Jiaxi Chen <jiaxi.chen@xxxxxxxxxxxxxxx>, Babu Moger <babu.moger@xxxxxxx>, Jim Mattson <jmattson@xxxxxxxxxx>, Sandipan Das <sandipan.das@xxxxxxx>, Lai Jiangshan <jiangshanlai@xxxxxxxxx>, Hans de Goede <hdegoede@xxxxxxxxxx>, Reinette Chatre <reinette.chatre@xxxxxxxxx>, Daniel Sneddon <daniel.sneddon@xxxxxxxxxxxxxxx>, Breno Leitao <leitao@xxxxxxxxxx>, Nikunj A Dadhania <nikunj@xxxxxxx>, Brian Gerst <brgerst@xxxxxxxxx>, Sami Tolvanen <samitolvanen@xxxxxxxxxx>, Alexander Potapenko <glider@xxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Arnd Bergmann <arnd@xxxxxxxx>, "Eric W . Biederman" <ebiederm@xxxxxxxxxxxx>, Kees Cook <keescook@xxxxxxxxxxxx>, Masami Hiramatsu <mhiramat@xxxxxxxxxx>, Masahiro Yamada <masahiroy@xxxxxxxxxx>, Ze Gao <zegao2021@xxxxxxxxx>, Fei Li <fei1.li@xxxxxxxxx>, Conghui <conghui.chen@xxxxxxxxx>, Ashok Raj <ashok.raj@xxxxxxxxx>, "Jason A . Donenfeld" <Jason@xxxxxxxxx>, Mark Rutland <mark.rutland@xxxxxxx>, Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>, Jiapeng Chong <jiapeng.chong@xxxxxxxxxxxxxxxxx>, Jane Malalane <jane.malalane@xxxxxxxxxx>, David Woodhouse <dwmw@xxxxxxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>, Yantengsi <siyanteng@xxxxxxxxxxx>, Christophe Leroy <christophe.leroy@xxxxxxxxxx>, Sathvika Vasireddy <sv@xxxxxxxxxxxxx>
- Delivery-date: Mon, 31 Jul 2023 07:03:10 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
From: "H. Peter Anvin (Intel)" <hpa@xxxxxxxxx>
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@xxxxxxxxx>
Tested-by: Shan Kang <shan.kang@xxxxxxxxx>
Signed-off-by: Xin Li <xin3.li@xxxxxxxxx>
---
arch/x86/include/asm/fred.h | 1 +
arch/x86/kernel/nmi.c | 19 +++++++++++++++++++
2 files changed, 20 insertions(+)
diff --git a/arch/x86/include/asm/fred.h b/arch/x86/include/asm/fred.h
index ad7b79130b1e..2a7c47dfd733 100644
--- a/arch/x86/include/asm/fred.h
+++ b/arch/x86/include/asm/fred.h
@@ -112,6 +112,7 @@ static __always_inline unsigned long fred_event_data(struct
pt_regs *regs)
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 a0c551846b35..f803e2bcd024 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++;
--
2.34.1
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