[Xen-devel] [PATCH 9/9] x86: PCID is unused when !PV

From: Jan Beulich <jbeulich@suse.com>
To: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: "George Dunlap" <George.Dunlap@eu.citrix.com>,
	"Andrew Cooper" <andrew.cooper3@citrix.com>,
	"Wei Liu" <wl@xen.org>, "Roger Pau Monné" <roger.pau@citrix.com>
Subject: [Xen-devel] [PATCH 9/9] x86: PCID is unused when !PV
Date: Wed, 11 Sep 2019 17:26:46 +0200	[thread overview]
Message-ID: <f44f12f3-6449-8014-43e4-1f08100be251@suse.com> (raw)
In-Reply-To: <f6accb8b-38d9-ad9a-ec68-992d75f36a88@suse.com>

This allows in particular some streamlining of the TLB flushing code
paths.

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/flushtlb.c
+++ b/xen/arch/x86/flushtlb.c
@@ -24,6 +24,11 @@
 #define WRAP_MASK (0x000003FFU)
 #endif
 
+#ifndef CONFIG_PV
+# undef X86_CR4_PCIDE
+# define X86_CR4_PCIDE 0
+#endif
+
 u32 tlbflush_clock = 1U;
 DEFINE_PER_CPU(u32, tlbflush_time);
 
--- a/xen/include/asm-x86/processor.h
+++ b/xen/include/asm-x86/processor.h
@@ -289,7 +289,11 @@ static inline unsigned long cr3_pa(unsig
 
 static inline unsigned int cr3_pcid(unsigned long cr3)
 {
+#ifdef CONFIG_PV
     return cr3 & X86_CR3_PCID_MASK;
+#else
+    return 0;
+#endif
 }
 
 static inline unsigned long read_cr4(void)
@@ -301,8 +305,12 @@ static inline void write_cr4(unsigned lo
 {
     struct cpu_info *info = get_cpu_info();
 
+#ifdef CONFIG_PV
     /* No global pages in case of PCIDs enabled! */
     ASSERT(!(val & X86_CR4_PGE) || !(val & X86_CR4_PCIDE));
+#else
+    ASSERT(!(val & X86_CR4_PCIDE));
+#endif
 
     /*
      * On hardware supporting FSGSBASE, the value in %cr4 is the kernel's
--- a/xen/include/asm-x86/pv/domain.h
+++ b/xen/include/asm-x86/pv/domain.h
@@ -50,8 +50,13 @@
  */
 static inline unsigned long get_pcid_bits(const struct vcpu *v, bool is_xpti)
 {
+#ifdef CONFIG_PV
     return X86_CR3_NOFLUSH | (is_xpti ? PCID_PV_XPTI : 0) |
            ((v->arch.flags & TF_kernel_mode) ? PCID_PV_PRIV : PCID_PV_USER);
+#else
+    ASSERT_UNREACHABLE();
+    return 0;
+#endif
 }
 
 #ifdef CONFIG_PV


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