[Xen-devel] [PATCH v3 3/3] x86: Clean up the Xen MSR infrastructure

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Rename them to guest_{rd,wr}msr_xen() for consistency, and because the _regs
suffix isn't very appropriate.

Update them to take a vcpu pointer rather than presuming that they act on
current, and switch to using X86EMUL_* return values.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Sergey Dyasli <sergey.dyasli@xxxxxxxxxx>

v3:
 * Clean up after splitting the series.
---
 xen/arch/x86/msr.c              |  6 ++----
 xen/arch/x86/traps.c            | 29 +++++++++++++----------------
 xen/include/asm-x86/processor.h |  4 ++--
 3 files changed, 17 insertions(+), 22 deletions(-)

diff --git a/xen/arch/x86/msr.c b/xen/arch/x86/msr.c
index cf0dc27..8f02a89 100644
--- a/xen/arch/x86/msr.c
+++ b/xen/arch/x86/msr.c
@@ -156,8 +156,7 @@ int guest_rdmsr(const struct vcpu *v, uint32_t msr, 
uint64_t *val)
 
         /* Fallthrough. */
     case 0x40000200 ... 0x400002ff:
-        ret = (rdmsr_hypervisor_regs(msr, val)
-               ? X86EMUL_OKAY : X86EMUL_EXCEPTION);
+        ret = guest_rdmsr_xen(v, msr, val);
         break;
 
     default:
@@ -277,8 +276,7 @@ int guest_wrmsr(struct vcpu *v, uint32_t msr, uint64_t val)
 
         /* Fallthrough. */
     case 0x40000200 ... 0x400002ff:
-        ret = (wrmsr_hypervisor_regs(msr, val) == 1
-               ? X86EMUL_OKAY : X86EMUL_EXCEPTION);
+        ret = guest_wrmsr_xen(v, msr, val);
         break;
 
     default:
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 7c17806..3988753 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -768,29 +768,25 @@ static void do_trap(struct cpu_user_regs *regs)
           trapnr, trapstr(trapnr), regs->error_code);
 }
 
-/* Returns 0 if not handled, and non-0 for success. */
-int rdmsr_hypervisor_regs(uint32_t idx, uint64_t *val)
+int guest_rdmsr_xen(const struct vcpu *v, uint32_t idx, uint64_t *val)
 {
-    struct domain *d = current->domain;
+    const struct domain *d = v->domain;
     /* Optionally shift out of the way of Viridian architectural MSRs. */
     uint32_t base = is_viridian_domain(d) ? 0x40000200 : 0x40000000;
 
     switch ( idx - base )
     {
     case 0: /* Write hypercall page MSR.  Read as zero. */
-    {
         *val = 0;
-        return 1;
-    }
+        return X86EMUL_OKAY;
     }
 
-    return 0;
+    return X86EMUL_EXCEPTION;
 }
 
-/* Returns 1 if handled, 0 if not and -Exx for error. */
-int wrmsr_hypervisor_regs(uint32_t idx, uint64_t val)
+int guest_wrmsr_xen(struct vcpu *v, uint32_t idx, uint64_t val)
 {
-    struct domain *d = current->domain;
+    struct domain *d = v->domain;
     /* Optionally shift out of the way of Viridian architectural MSRs. */
     uint32_t base = is_viridian_domain(d) ? 0x40000200 : 0x40000000;
 
@@ -809,7 +805,7 @@ int wrmsr_hypervisor_regs(uint32_t idx, uint64_t val)
             gdprintk(XENLOG_WARNING,
                      "wrmsr hypercall page index %#x unsupported\n",
                      page_index);
-            return 0;
+            return X86EMUL_EXCEPTION;
         }
 
         page = get_page_from_gfn(d, gmfn, &t, P2M_ALLOC);
@@ -822,13 +818,13 @@ int wrmsr_hypervisor_regs(uint32_t idx, uint64_t val)
             if ( p2m_is_paging(t) )
             {
                 p2m_mem_paging_populate(d, gmfn);
-                return -ERESTART;
+                return X86EMUL_RETRY;
             }
 
             gdprintk(XENLOG_WARNING,
                      "Bad GMFN %lx (MFN %#"PRI_mfn") to MSR %08x\n",
                      gmfn, mfn_x(page ? page_to_mfn(page) : INVALID_MFN), 
base);
-            return 0;
+            return X86EMUL_EXCEPTION;
         }
 
         hypercall_page = __map_domain_page(page);
@@ -836,11 +832,12 @@ int wrmsr_hypervisor_regs(uint32_t idx, uint64_t val)
         unmap_domain_page(hypercall_page);
 
         put_page_and_type(page);
-        return 1;
-    }
+        return X86EMUL_OKAY;
     }
 
-    return 0;
+    default:
+        return X86EMUL_EXCEPTION;
+    }
 }
 
 void cpuid_hypervisor_leaves(const struct vcpu *v, uint32_t leaf,
diff --git a/xen/include/asm-x86/processor.h b/xen/include/asm-x86/processor.h
index a166802..03555e1 100644
--- a/xen/include/asm-x86/processor.h
+++ b/xen/include/asm-x86/processor.h
@@ -554,8 +554,8 @@ unsigned long alloc_stub_page(unsigned int cpu, unsigned 
long *mfn);
 
 void cpuid_hypervisor_leaves(const struct vcpu *v, uint32_t leaf,
                              uint32_t subleaf, struct cpuid_leaf *res);
-int rdmsr_hypervisor_regs(uint32_t idx, uint64_t *val);
-int wrmsr_hypervisor_regs(uint32_t idx, uint64_t val);
+int guest_rdmsr_xen(const struct vcpu *v, uint32_t idx, uint64_t *val);
+int guest_wrmsr_xen(struct vcpu *v, uint32_t idx, uint64_t val);
 
 void microcode_set_module(unsigned int);
 int microcode_update(XEN_GUEST_HANDLE_PARAM(const_void), unsigned long len);
-- 
2.1.4


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