File xsa297-0b.patch of Package xen.12882

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File xsa297-0b.patch of Package xen.12882

x86/msr: Definitions for MSR_INTEL_CORE_THREAD_COUNT

This is a model specific register which details the current configuration
cores and threads in the package.  Because of how Hyperthread and Core
configuration works works in firmware, the MSR it is de-facto constant and
will remain unchanged until the next system reset.

It is a read only MSR (so unilaterally reject writes), but for now retain its
leaky-on-read properties.  Further CPUID/MSR work is required before we can
start virtualising a consistent topology to the guest, and retaining the old
behaviour is the safest course of action.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4010,6 +4010,7 @@ int hvm_msr_write_intercept(unsigned int
         wrmsrl(MSR_FLUSH_CMD, msr_content);
         break;
 
+    case MSR_INTEL_CORE_THREAD_COUNT:
     case MSR_ARCH_CAPABILITIES:
         /* Read-only */
     case MSR_TSX_FORCE_ABORT:
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -2901,6 +2901,7 @@ static int emulate_privileged_op(struct
                 wrmsrl(regs->_ecx, msr_content);
             break;
 
+        case MSR_INTEL_CORE_THREAD_COUNT:
         case MSR_INTEL_PLATFORM_INFO:
         case MSR_ARCH_CAPABILITIES:
             /* The MSR is read-only. */
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -31,6 +31,10 @@
 #define EFER_LMSLE		(1<<_EFER_LMSLE)
 #define EFER_FFXSE		(1<<_EFER_FFXSE)
 
+#define MSR_INTEL_CORE_THREAD_COUNT     0x00000035
+#define MSR_CTC_THREAD_MASK             0x0000ffff
+#define MSR_CTC_CORE_MASK               0xffff0000
+
 /* Speculation Controls. */
 #define MSR_SPEC_CTRL			0x00000048
 #define SPEC_CTRL_IBRS			(_AC(1, ULL) << 0)

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File xsa297-0b.patch of Package xen.12882

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