[Xen-devel] [PATCH v2 2/4] x86/setup: Intoduce XEN_MSR_STAR

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Xen's choice of the MSR_STAR value is constant across all pcpus.  Introduce a
new define and use it to avoid the opencoding in subarch_percpu_traps_init()
and restore_rest_processor_state().

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>

v2:
 * Drop all the adjustments to MSR_CSTAR
---
 xen/arch/x86/acpi/suspend.c     | 4 ++--
 xen/arch/x86/x86_64/traps.c     | 4 ++--
 xen/include/asm-x86/processor.h | 3 +++
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/acpi/suspend.c b/xen/arch/x86/acpi/suspend.c
index d5c67ee..0dba3e5 100644
--- a/xen/arch/x86/acpi/suspend.c
+++ b/xen/arch/x86/acpi/suspend.c
@@ -54,8 +54,8 @@ void restore_rest_processor_state(void)
     /* Recover syscall MSRs */
     wrmsrl(MSR_LSTAR, saved_lstar);
     wrmsrl(MSR_CSTAR, saved_cstar);
-    wrmsr(MSR_STAR, 0, (FLAT_RING3_CS32<<16) | __HYPERVISOR_CS);
-    wrmsr(MSR_SYSCALL_MASK, XEN_SYSCALL_MASK, 0U);
+    wrmsrl(MSR_STAR, XEN_MSR_STAR);
+    wrmsrl(MSR_SYSCALL_MASK, XEN_SYSCALL_MASK);
 
     wrfsbase(saved_fs_base);
     wrgsbase(saved_gs_base);
diff --git a/xen/arch/x86/x86_64/traps.c b/xen/arch/x86/x86_64/traps.c
index fc8cde6..252d2d0 100644
--- a/xen/arch/x86/x86_64/traps.c
+++ b/xen/arch/x86/x86_64/traps.c
@@ -415,8 +415,8 @@ void subarch_percpu_traps_init(void)
     unmap_domain_page(stub_page);
 
     /* Common SYSCALL parameters. */
-    wrmsr(MSR_STAR, 0, ((unsigned int)FLAT_RING3_CS32 << 16) | 
__HYPERVISOR_CS);
-    wrmsr(MSR_SYSCALL_MASK, XEN_SYSCALL_MASK, 0U);
+    wrmsrl(MSR_STAR, XEN_MSR_STAR);
+    wrmsrl(MSR_SYSCALL_MASK, XEN_SYSCALL_MASK);
 }
 
 void init_int80_direct_trap(struct vcpu *v)
diff --git a/xen/include/asm-x86/processor.h b/xen/include/asm-x86/processor.h
index 7735bc2..843f072 100644
--- a/xen/include/asm-x86/processor.h
+++ b/xen/include/asm-x86/processor.h
@@ -87,6 +87,9 @@
 
 #define XEN_CR4_PV32_BITS (X86_CR4_SMEP|X86_CR4_SMAP)
 
+/* Common SYSCALL parameters. */
+#define XEN_MSR_STAR (((uint64_t)FLAT_RING3_CS32 << 48) |   \
+                      ((uint64_t)__HYPERVISOR_CS << 32))
 #define XEN_SYSCALL_MASK (X86_EFLAGS_AC|X86_EFLAGS_VM|X86_EFLAGS_RF|    \
                           X86_EFLAGS_NT|X86_EFLAGS_DF|X86_EFLAGS_IF|    \
                           X86_EFLAGS_TF)
-- 
2.1.4


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