[PATCH v7 03/19] x86/resctrl: Add PLZA MSR definition and field layout

[Babu Moger <babu.moger@amd.com>]

Privilege Level Zero Association (PLZA) enables a CPU to use a different
CLOSID and/or RMID association when executing in kernel mode than those
used in user mode.

PLZA is programmed per-CPU through MSR_IA32_PQR_PLZA_ASSOC, which contains
the kernel mode CLOSID and RMID, an enable bit for each, and a bit that
enables PLZA on the CPU. All fields except the PLZA enable bit must be
programmed identically on every CPU in a domain.

Make the register and its field layout available in preparation for resctrl
support of PLZA.

Signed-off-by: Babu Moger <babu.moger@amd.com>
---
v7: Updated changelog(Reinette) with minor changes.
    Minor code comment update.

v6: Updated the code comments to match general format (members first and
    details after).
    changelog update.

v5: Sashiko reported:
    https://sashiko.dev/#/patchset/cover.1783461016.git.babu.moger%40amd.com?part=3
    Fix the union truncate issue on 32 bit systems by using u64.
    Updated the changelog and code comments.

v4: Re-wrote the changelog and code comment.

v3: No code changes. Patch order changed. Improved changelog.

v2: No changes. Just rebasing on top of the latest tip branch.
---
 arch/x86/include/asm/msr-index.h       |  1 +
 arch/x86/kernel/cpu/resctrl/internal.h | 49 ++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index c0914829a925..13f81a0587b4 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -1306,6 +1306,7 @@
 /* - AMD: */
 #define MSR_IA32_MBA_BW_BASE		0xc0000200
 #define MSR_IA32_SMBA_BW_BASE		0xc0000280
+#define MSR_IA32_PQR_PLZA_ASSOC		0xc00003fc
 #define MSR_IA32_L3_QOS_ABMC_CFG	0xc00003fd
 #define MSR_IA32_L3_QOS_EXT_CFG		0xc00003ff
 #define MSR_IA32_EVT_CFG_BASE		0xc0000400
diff --git a/arch/x86/kernel/cpu/resctrl/internal.h b/arch/x86/kernel/cpu/resctrl/internal.h
index 03cb22f4e607..d75013ede600 100644
--- a/arch/x86/kernel/cpu/resctrl/internal.h
+++ b/arch/x86/kernel/cpu/resctrl/internal.h
@@ -226,6 +226,55 @@ union l3_qos_abmc_cfg {
 	unsigned long full;
 };
 
+/*
+ * Privilege Level Zero Association (PLZA) is configured via
+ * MSR_IA32_PQR_PLZA_ASSOC.
+ *
+ * @rmid		: RMID programmed for PLZA.
+ * @reserved1		: Reserved.
+ * @rmid_en		: Enable RMID for PLZA.
+ * @closid		: CLOSID programmed for PLZA.
+ * @reserved2		: Reserved.
+ * @closid_en		: Enable CLOSID for PLZA.
+ * @reserved3		: Reserved.
+ * @plza_en		: Enable PLZA. When enabled, PLZA applies to the
+ *			  given CPU.
+ *
+ * The MSR_IA32_PQR_PLZA_ASSOC must be programmed on every CPU in a QoS
+ * domain. Each domain supports a single PLZA CLOSID and/or RMID, and all
+ * the fields except @plza_en must be programmed identically in a domain
+ * to ensure consistent behavior.
+ *
+ * CLOSID and RMID selections are controlled independently. When PLZA is
+ * enabled (@plza_en = 1), CPL0 uses CLOSID and RMID values from
+ * MSR_IA32_PQR_PLZA_ASSOC depending on the corresponding enable bits. When
+ * PLZA is disabled (@plza_en = 0), the CLOSID and RMID are always taken
+ * from MSR_IA32_PQR_ASSOC regardless of privilege level.
+ *
+ * - @rmid_en = 1: use the RMID from MSR_IA32_PQR_PLZA_ASSOC if @plza_en = 1.
+ * - @rmid_en = 0: use the RMID from MSR_IA32_PQR_ASSOC.
+ * - @closid_en = 1: use the CLOSID from MSR_IA32_PQR_PLZA_ASSOC if @plza_en = 1.
+ * - @closid_en = 0: use the CLOSID from MSR_IA32_PQR_ASSOC.
+ *
+ * This allows PLZA to override only RMID, only CLOSID, or both. If both
+ * @rmid_en and @closid_en are clear, the effective behavior is the same as
+ * when PLZA is disabled, with RMID and CLOSID used from MSR_IA32_PQR_ASSOC
+ * irrespective of privilege level.
+ */
+union msr_pqr_plza_assoc {
+	struct {
+		u64	rmid		:12,
+			reserved1	:19,
+			rmid_en		: 1,
+			closid		: 4,
+			reserved2	:11,
+			closid_en	: 1,
+			reserved3	:15,
+			plza_en		: 1;
+	} split;
+	u64	full;
+};
+
 void rdt_ctrl_update(void *arg);
 
 int rdt_get_l3_mon_config(struct rdt_resource *r);
-- 
2.43.0