linux-kernel - [RFC][PATCH 1/6] x86/power: De-paravirt restore_processor

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Message-ID: <20230112143825.584639584@infradead.org>
Date:   Thu, 12 Jan 2023 15:31:42 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     x86@...nel.org, Joan Bruguera <joanbrugueram@...il.com>
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        Juergen Gross <jgross@...e.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        xen-devel <xen-devel@...ts.xenproject.org>,
        Jan Beulich <jbeulich@...e.com>,
        Roger Pau Monne <roger.pau@...rix.com>,
        Kees Cook <keescook@...omium.org>, mark.rutland@....com
Subject: [RFC][PATCH 1/6] x86/power: De-paravirt restore_processor_state()

Since Xen PV doesn't use restore_processor_state(), and we're going to
have to avoid CALL/RET until at least GS is restored, de-paravirt the
easy bits.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/power/cpu.c |   24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

--- a/arch/x86/power/cpu.c
+++ b/arch/x86/power/cpu.c
@@ -197,25 +197,25 @@ static void notrace __restore_processor_
 	struct cpuinfo_x86 *c;
 
 	if (ctxt->misc_enable_saved)
-		wrmsrl(MSR_IA32_MISC_ENABLE, ctxt->misc_enable);
+		native_wrmsrl(MSR_IA32_MISC_ENABLE, ctxt->misc_enable);
 	/*
 	 * control registers
 	 */
 	/* cr4 was introduced in the Pentium CPU */
 #ifdef CONFIG_X86_32
 	if (ctxt->cr4)
-		__write_cr4(ctxt->cr4);
+		native_write_cr4(ctxt->cr4);
 #else
 /* CONFIG X86_64 */
-	wrmsrl(MSR_EFER, ctxt->efer);
-	__write_cr4(ctxt->cr4);
+	native_wrmsrl(MSR_EFER, ctxt->efer);
+	native_write_cr4(ctxt->cr4);
 #endif
-	write_cr3(ctxt->cr3);
-	write_cr2(ctxt->cr2);
-	write_cr0(ctxt->cr0);
+	native_write_cr3(ctxt->cr3);
+	native_write_cr2(ctxt->cr2);
+	native_write_cr0(ctxt->cr0);
 
 	/* Restore the IDT. */
-	load_idt(&ctxt->idt);
+	native_load_idt(&ctxt->idt);
 
 	/*
 	 * Just in case the asm code got us here with the SS, DS, or ES
@@ -230,7 +230,7 @@ static void notrace __restore_processor_
 	 * handlers or in complicated helpers like load_gs_index().
 	 */
 #ifdef CONFIG_X86_64
-	wrmsrl(MSR_GS_BASE, ctxt->kernelmode_gs_base);
+	native_wrmsrl(MSR_GS_BASE, ctxt->kernelmode_gs_base);
 #else
 	loadsegment(fs, __KERNEL_PERCPU);
 #endif
@@ -246,15 +246,15 @@ static void notrace __restore_processor_
 	loadsegment(ds, ctxt->es);
 	loadsegment(es, ctxt->es);
 	loadsegment(fs, ctxt->fs);
-	load_gs_index(ctxt->gs);
+	native_load_gs_index(ctxt->gs);
 
 	/*
 	 * Restore FSBASE and GSBASE after restoring the selectors, since
 	 * restoring the selectors clobbers the bases.  Keep in mind
 	 * that MSR_KERNEL_GS_BASE is horribly misnamed.
 	 */
-	wrmsrl(MSR_FS_BASE, ctxt->fs_base);
-	wrmsrl(MSR_KERNEL_GS_BASE, ctxt->usermode_gs_base);
+	native_wrmsrl(MSR_FS_BASE, ctxt->fs_base);
+	native_wrmsrl(MSR_KERNEL_GS_BASE, ctxt->usermode_gs_base);
 #else
 	loadsegment(gs, ctxt->gs);
 #endif