[PATCH v3 2/6] x86/sev: Add support for enabling RMPOPT

[Ashish Kalra <Ashish.Kalra@amd.com>]

From: Ashish Kalra <ashish.kalra@amd.com>

The new RMPOPT instruction helps manage per-CPU RMP optimization
structures inside the CPU. It takes a 1GB-aligned physical address
and either returns the status of the optimizations or tries to enable
the optimizations.

Per-CPU RMPOPT tables support at most 2 TB of addressable memory for
RMP optimizations.

Initialize the per-CPU RMPOPT table base to the starting physical
address. This enables RMP optimization for up to 2 TB of system RAM on
all CPUs.

Suggested-by: Thomas Lendacky <thomas.lendacky@amd.com>
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
 arch/x86/include/asm/msr-index.h |  3 +++
 arch/x86/virt/svm/sev.c          | 26 ++++++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index be3e3cc963b2..9c8a6dfd7891 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -758,6 +758,9 @@
 #define MSR_AMD64_SEG_RMP_ENABLED_BIT	0
 #define MSR_AMD64_SEG_RMP_ENABLED	BIT_ULL(MSR_AMD64_SEG_RMP_ENABLED_BIT)
 #define MSR_AMD64_RMP_SEGMENT_SHIFT(x)	(((x) & GENMASK_ULL(13, 8)) >> 8)
+#define MSR_AMD64_RMPOPT_BASE		0xc0010139
+#define MSR_AMD64_RMPOPT_ENABLE_BIT	0
+#define MSR_AMD64_RMPOPT_ENABLE		BIT_ULL(MSR_AMD64_RMPOPT_ENABLE_BIT)
 
 #define MSR_SVSM_CAA			0xc001f000
 
diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
index e35fac0a8a3d..dc6a8e102cdc 100644
--- a/arch/x86/virt/svm/sev.c
+++ b/arch/x86/virt/svm/sev.c
@@ -477,6 +477,30 @@ static bool __init setup_rmptable(void)
 	return true;
 }
 
+static __init void configure_and_enable_rmpopt(void)
+{
+	phys_addr_t pa_start = ALIGN_DOWN(PFN_PHYS(min_low_pfn), SZ_1G);
+	u64 rmpopt_base = pa_start | MSR_AMD64_RMPOPT_ENABLE;
+	int cpu;
+
+	if (!cpu_feature_enabled(X86_FEATURE_RMPOPT))
+		return;
+
+	if (!(rmp_cfg & MSR_AMD64_SEG_RMP_ENABLED)) {
+		pr_notice("RMPOPT optimizations not enabled, segmented RMP required\n");
+		return;
+	}
+
+	/*
+	 * Per-CPU RMPOPT tables support at most 2 TB of addressable memory
+	 * for RMP optimizations. Initialize the per-CPU RMPOPT table base
+	 * to the starting physical address to enable RMP optimizations for
+	 * up to 2 TB of system RAM on all CPUs.
+	 */
+	for_each_online_cpu(cpu)
+		wrmsrq_on_cpu(cpu, MSR_AMD64_RMPOPT_BASE, rmpopt_base);
+}
+
 /*
  * Do the necessary preparations which are verified by the firmware as
  * described in the SNP_INIT_EX firmware command description in the SNP
@@ -530,6 +554,8 @@ int __init snp_rmptable_init(void)
 	 */
 	crash_kexec_post_notifiers = true;
 
+	configure_and_enable_rmpopt();
+
 	return 0;
 }
 
-- 
2.43.0