Moving this function out of mce_intel.c would make it possible to disable
build of Intel MCE code later on, because the function gets called from
common x86 code.

Add internal check for CONFIG_INTEL option, as MCG_LMCE_P bit is currently
specific to Intel CPUs only.

Also replace boilerplate code that checks for MCG_LMCE_P flag with
vmce_has_lmce(), which might contribute to readability a bit.

Signed-off-by: Sergiy Kibrik <Sergiy_Kibrik@epam.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
CC: Jan Beulich <jbeulich@suse.com>
---
changes in v2:
 - move vmce_has_lmce() to cpu/mcheck/mce.h
 - move IS_ENABLED(CONFIG_INTEL) check inside vmce_has_lmce()
 - changed description
---
 xen/arch/x86/cpu/mcheck/mce.h       | 5 +++++
 xen/arch/x86/cpu/mcheck/mce_intel.c | 4 ----
 xen/arch/x86/cpu/mcheck/vmce.c      | 5 ++---
 xen/arch/x86/include/asm/mce.h      | 1 -
 xen/arch/x86/msr.c                  | 2 ++
 5 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/xen/arch/x86/cpu/mcheck/mce.h b/xen/arch/x86/cpu/mcheck/mce.h
index 4806405f96..d6d56aa232 100644
--- a/xen/arch/x86/cpu/mcheck/mce.h
+++ b/xen/arch/x86/cpu/mcheck/mce.h
@@ -170,6 +170,11 @@ static inline int mce_bank_msr(const struct vcpu *v, uint32_t msr)
     return 0;
 }
 
+static inline bool vmce_has_lmce(const struct vcpu *v)
+{
+    return IS_ENABLED(CONFIG_INTEL) && v->arch.vmce.mcg_cap & MCG_LMCE_P;
+}
+
 struct mce_callbacks {
     void (*handler)(const struct cpu_user_regs *regs);
     bool (*check_addr)(uint64_t status, uint64_t misc, int addr_type);
diff --git a/xen/arch/x86/cpu/mcheck/mce_intel.c b/xen/arch/x86/cpu/mcheck/mce_intel.c
index 3f5199b531..af43281cc6 100644
--- a/xen/arch/x86/cpu/mcheck/mce_intel.c
+++ b/xen/arch/x86/cpu/mcheck/mce_intel.c
@@ -1050,7 +1050,3 @@ int vmce_intel_rdmsr(const struct vcpu *v, uint32_t msr, uint64_t *val)
     return 1;
 }
 
-bool vmce_has_lmce(const struct vcpu *v)
-{
-    return v->arch.vmce.mcg_cap & MCG_LMCE_P;
-}
diff --git a/xen/arch/x86/cpu/mcheck/vmce.c b/xen/arch/x86/cpu/mcheck/vmce.c
index 353d4f19b2..94d1f021e1 100644
--- a/xen/arch/x86/cpu/mcheck/vmce.c
+++ b/xen/arch/x86/cpu/mcheck/vmce.c
@@ -199,7 +199,7 @@ int vmce_rdmsr(uint32_t msr, uint64_t *val)
          * bits are always set in guest MSR_IA32_FEATURE_CONTROL by Xen, so it
          * does not need to check them here.
          */
-        if ( cur->arch.vmce.mcg_cap & MCG_LMCE_P )
+        if ( vmce_has_lmce(cur) )
         {
             *val = cur->arch.vmce.mcg_ext_ctl;
             mce_printk(MCE_VERBOSE, "MCE: %pv: rd MCG_EXT_CTL %#"PRIx64"\n",
@@ -324,8 +324,7 @@ int vmce_wrmsr(uint32_t msr, uint64_t val)
         break;
 
     case MSR_IA32_MCG_EXT_CTL:
-        if ( (cur->arch.vmce.mcg_cap & MCG_LMCE_P) &&
-             !(val & ~MCG_EXT_CTL_LMCE_EN) )
+        if ( vmce_has_lmce(cur) && !(val & ~MCG_EXT_CTL_LMCE_EN) )
             cur->arch.vmce.mcg_ext_ctl = val;
         else
             ret = -1;
diff --git a/xen/arch/x86/include/asm/mce.h b/xen/arch/x86/include/asm/mce.h
index 6ce56b5b85..2ec47a71ae 100644
--- a/xen/arch/x86/include/asm/mce.h
+++ b/xen/arch/x86/include/asm/mce.h
@@ -41,7 +41,6 @@ extern void vmce_init_vcpu(struct vcpu *v);
 extern int vmce_restore_vcpu(struct vcpu *v, const struct hvm_vmce_vcpu *ctxt);
 extern int vmce_wrmsr(uint32_t msr, uint64_t val);
 extern int vmce_rdmsr(uint32_t msr, uint64_t *val);
-extern bool vmce_has_lmce(const struct vcpu *v);
 extern int vmce_enable_mca_cap(struct domain *d, uint64_t cap);
 
 DECLARE_PER_CPU(unsigned int, nr_mce_banks);
diff --git a/xen/arch/x86/msr.c b/xen/arch/x86/msr.c
index 9babd441f9..b0ec96f021 100644
--- a/xen/arch/x86/msr.c
+++ b/xen/arch/x86/msr.c
@@ -24,6 +24,8 @@
 
 #include <public/hvm/params.h>
 
+#include "cpu/mcheck/mce.h"
+
 DEFINE_PER_CPU(uint32_t, tsc_aux);
 
 int init_vcpu_msr_policy(struct vcpu *v)
-- 
2.25.1

On 02.05.2024 11:14, Sergiy Kibrik wrote:
> Moving this function out of mce_intel.c would make it possible to disable
> build of Intel MCE code later on, because the function gets called from
> common x86 code.
> 
> Add internal check for CONFIG_INTEL option, as MCG_LMCE_P bit is currently
> specific to Intel CPUs only.

My previously voiced concern regarding this was not addressed. If ...

> --- a/xen/arch/x86/cpu/mcheck/mce.h
> +++ b/xen/arch/x86/cpu/mcheck/mce.h
> @@ -170,6 +170,11 @@ static inline int mce_bank_msr(const struct vcpu *v, uint32_t msr)
>      return 0;
>  }
>  
> +static inline bool vmce_has_lmce(const struct vcpu *v)
> +{
> +    return IS_ENABLED(CONFIG_INTEL) && v->arch.vmce.mcg_cap & MCG_LMCE_P;

... the IS_ENABLED() indeed is to stay, the & wants parenthesizing.

Jan

06.05.24 14:18, Jan Beulich:
> On 02.05.2024 11:14, Sergiy Kibrik wrote:
>> Moving this function out of mce_intel.c would make it possible to disable
>> build of Intel MCE code later on, because the function gets called from
>> common x86 code.
>>
>> Add internal check for CONFIG_INTEL option, as MCG_LMCE_P bit is currently
>> specific to Intel CPUs only.
> My previously voiced concern regarding this was not addressed. If ...

I misunderstood you comment to v1 patch.
I'll drop checks for CONFIG_INTEL, I see now that we don't really need one.

   -Sergiy