linux-kernel - [PATCH 2/4] x86/xen: use specific Xen pv interrupt entry for DF

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Date:   Mon, 16 Nov 2020 16:22:59 +0100
From:   Juergen Gross <jgross@...e.com>
To:     xen-devel@...ts.xenproject.org, x86@...nel.org,
        linux-kernel@...r.kernel.org
Cc:     Juergen Gross <jgross@...e.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Stefano Stabellini <sstabellini@...nel.org>
Subject: [PATCH 2/4] x86/xen: use specific Xen pv interrupt entry for DF

Xen PV guests don't use IST. For double fault interrupts switch to
the same model as NMI.

Signed-off-by: Juergen Gross <jgross@...e.com>
---
 arch/x86/include/asm/idtentry.h | 3 +++
 arch/x86/xen/enlighten_pv.c     | 8 +++++++-
 arch/x86/xen/xen-asm.S          | 2 +-
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 3505c0396fa5..b35825392547 100644
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -611,6 +611,9 @@ DECLARE_IDTENTRY_RAW(X86_TRAP_DB,	xenpv_exc_debug);
 
 /* #DF */
 DECLARE_IDTENTRY_DF(X86_TRAP_DF,	exc_double_fault);
+#ifdef CONFIG_XEN_PV
+DECLARE_IDTENTRY_RAW_ERRORCODE(X86_TRAP_DF,	xenpv_exc_double_fault);
+#endif
 
 /* #VC */
 #ifdef CONFIG_AMD_MEM_ENCRYPT
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
index 9f5e44c1f70a..803fbcb398c4 100644
--- a/arch/x86/xen/enlighten_pv.c
+++ b/arch/x86/xen/enlighten_pv.c
@@ -571,6 +571,12 @@ DEFINE_IDTENTRY_RAW(xenpv_exc_nmi)
 	exc_nmi(regs);
 }
 
+DEFINE_IDTENTRY_RAW_ERRORCODE(xenpv_exc_double_fault)
+{
+	/* On Xen PV, DF doesn't use IST.  The C part is the sane as native. */
+	exc_double_fault(regs, error_code);
+}
+
 DEFINE_IDTENTRY_RAW(xenpv_exc_debug)
 {
 	/*
@@ -615,7 +621,7 @@ struct trap_array_entry {
 
 static struct trap_array_entry trap_array[] = {
 	TRAP_ENTRY_REDIR(exc_debug,			true  ),
-	TRAP_ENTRY(exc_double_fault,			true  ),
+	TRAP_ENTRY_REDIR(exc_double_fault,		true  ),
 #ifdef CONFIG_X86_MCE
 	TRAP_ENTRY_REDIR(exc_machine_check,		true  ),
 #endif
diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S
index bc2586730a5b..1d054c915046 100644
--- a/arch/x86/xen/xen-asm.S
+++ b/arch/x86/xen/xen-asm.S
@@ -161,7 +161,7 @@ xen_pv_trap asm_exc_overflow
 xen_pv_trap asm_exc_bounds
 xen_pv_trap asm_exc_invalid_op
 xen_pv_trap asm_exc_device_not_available
-xen_pv_trap asm_exc_double_fault
+xen_pv_trap asm_xenpv_exc_double_fault
 xen_pv_trap asm_exc_coproc_segment_overrun
 xen_pv_trap asm_exc_invalid_tss
 xen_pv_trap asm_exc_segment_not_present
-- 
2.26.2