linux-kernel - [PATCH v6 36/76] x86/head/64: Load IDT earlier

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Message-Id: <20200824085511.7553-37-joro@8bytes.org>
Date:   Mon, 24 Aug 2020 10:54:31 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     x86@...nel.org
Cc:     Joerg Roedel <joro@...tes.org>, Joerg Roedel <jroedel@...e.de>,
        hpa@...or.com, Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Jiri Slaby <jslaby@...e.cz>,
        Dan Williams <dan.j.williams@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Juergen Gross <jgross@...e.com>,
        Kees Cook <keescook@...omium.org>,
        David Rientjes <rientjes@...gle.com>,
        Cfir Cohen <cfir@...gle.com>,
        Erdem Aktas <erdemaktas@...gle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mike Stunes <mstunes@...are.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Martin Radev <martin.b.radev@...il.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Subject: [PATCH v6 36/76] x86/head/64: Load IDT earlier

From: Joerg Roedel <jroedel@...e.de>

Load the IDT right after switching to virtual addresses in head_64.S
so that the kernel can handle #VC exceptions.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
Link: https://lore.kernel.org/r/20200724160336.5435-36-joro@8bytes.org
---
 arch/x86/include/asm/setup.h |  3 +++
 arch/x86/kernel/head64.c     |  3 +++
 arch/x86/kernel/head_64.S    |  5 +++++
 arch/x86/kernel/idt.c        | 23 +++++++++++++++++++++++
 4 files changed, 34 insertions(+)

diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index 8aa6ba0427b0..5c09f50ecf1c 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -50,6 +50,8 @@ extern unsigned long __startup_64(unsigned long physaddr, struct boot_params *bp
 extern unsigned long __startup_secondary_64(void);
 extern void startup_64_setup_env(unsigned long physbase);
 extern int early_make_pgtable(unsigned long address);
+extern void early_idt_setup_early_handler(unsigned long physaddr);
+extern void early_load_idt(void);
 
 #ifdef CONFIG_X86_INTEL_MID
 extern void x86_intel_mid_early_setup(void);
@@ -66,6 +68,7 @@ static inline void x86_ce4100_early_setup(void) { }
 #ifndef _SETUP
 
 #include <asm/espfix.h>
+#include <asm/sections.h>
 #include <linux/kernel.h>
 
 /*
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 8703292a35e9..096b09d06d1c 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -286,6 +286,9 @@ unsigned long __head __startup_64(unsigned long physaddr,
 		}
 	}
 
+	/* Setup IDT with early handlers */
+	early_idt_setup_early_handler(physaddr);
+
 	/*
 	 * Return the SME encryption mask (if SME is active) to be used as a
 	 * modifier for the initial pgdir entry programmed into CR3.
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index a5e1939d1dc9..28de83fecda3 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -206,6 +206,11 @@ SYM_CODE_START(secondary_startup_64)
 	 */
 	movq initial_stack(%rip), %rsp
 
+	/* Load IDT */
+	pushq	%rsi
+	call	early_load_idt
+	popq	%rsi
+
 	/* Check if nx is implemented */
 	movl	$0x80000001, %eax
 	cpuid
diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index c19773174221..e2777cc264f5 100644
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -10,6 +10,7 @@
 #include <asm/proto.h>
 #include <asm/desc.h>
 #include <asm/hw_irq.h>
+#include <asm/setup.h>
 
 struct idt_data {
 	unsigned int	vector;
@@ -385,3 +386,25 @@ void __init alloc_intr_gate(unsigned int n, const void *addr)
 	if (!WARN_ON(test_and_set_bit(n, system_vectors)))
 		set_intr_gate(n, addr);
 }
+
+void __init early_idt_setup_early_handler(unsigned long physaddr)
+{
+	gate_desc *idt;
+	int i;
+
+	idt = fixup_pointer(idt_table, physaddr);
+
+	for (i = 0; i < NUM_EXCEPTION_VECTORS; i++) {
+		struct idt_data data;
+		gate_desc desc;
+
+		init_idt_data(&data, i, early_idt_handler_array[i]);
+		idt_init_desc(&desc, &data);
+		native_write_idt_entry(idt, i, &desc);
+	}
+}
+
+void early_load_idt(void)
+{
+	load_idt(&idt_descr);
+}
-- 
2.28.0