[PATCH v12 3/5] x86/sev: Initialize RMPOPT configuration MSRs

[Ashish Kalra]

From: Ashish Kalra <ashish.kalra@xxxxxxx>

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.

Additionally, add support to setup and enable RMPOPT once SNP is
enabled and initialized.

Suggested-by: Thomas Lendacky <thomas.lendacky@xxxxxxx>
Suggested-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Suggested-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Suggested-by: K Prateek Nayak <kprateek.nayak@xxxxxxx>
Reviewed-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
---
 arch/x86/include/asm/msr-index.h |  3 ++
 arch/x86/include/asm/sev.h       |  2 +
 arch/x86/virt/svm/sev.c          | 75 +++++++++++++++++++++++++++++---
 drivers/crypto/ccp/sev-dev.c     |  2 +
 4 files changed, 77 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 18c4be75e927..d2cb0a7cd0a2 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -761,6 +761,9 @@
 #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/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 594cfa19cbd4..6fd72a44a51e 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -662,6 +662,7 @@ static inline void snp_leak_pages(u64 pfn, unsigned int pages)
 	__snp_leak_pages(pfn, pages, true);
 }
 int snp_prepare(void);
+void snp_setup_rmpopt(void);
 void snp_shutdown(void);
 #else
 static inline bool snp_probe_rmptable_info(void) { return false; }
@@ -680,6 +681,7 @@ static inline void snp_leak_pages(u64 pfn, unsigned int npages) {}
 static inline void kdump_sev_callback(void) { }
 static inline void snp_fixup_e820_tables(void) {}
 static inline int snp_prepare(void) { return -ENODEV; }
+static inline void snp_setup_rmpopt(void) {}
 static inline void snp_shutdown(void) {}
 #endif
 
diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c
index 558f7924a3f8..923b7869acd1 100644
--- a/arch/x86/virt/svm/sev.c
+++ b/arch/x86/virt/svm/sev.c
@@ -124,6 +124,9 @@ static void *rmp_bookkeeping __ro_after_init;
 
 static u64 probed_rmp_base, probed_rmp_size;
 
+static cpumask_var_t rmpopt_cpumask;
+static phys_addr_t rmpopt_pa_start;
+
 static LIST_HEAD(snp_leaked_pages_list);
 static DEFINE_SPINLOCK(snp_leaked_pages_list_lock);
 
@@ -555,6 +558,17 @@ int snp_prepare(void)
 }
 EXPORT_SYMBOL_FOR_MODULES(snp_prepare, "ccp");
 
+static void snp_cleanup_rmpopt(void)
+{
+	int cpu;
+
+	for_each_cpu(cpu, rmpopt_cpumask)
+		wrmsrq_on_cpu(cpu, MSR_AMD64_RMPOPT_BASE, 0);
+
+	free_cpumask_var(rmpopt_cpumask);
+	rmpopt_pa_start = 0;
+}
+
 void snp_shutdown(void)
 {
 	u64 syscfg;
@@ -563,6 +577,9 @@ void snp_shutdown(void)
 	if (syscfg & MSR_AMD64_SYSCFG_SNP_EN)
 		return;
 
+	/* Disable RMPOPT while CPU hotplug is disabled. */
+	snp_cleanup_rmpopt();
+
 	clear_rmp();
 	on_each_cpu(mfd_reconfigure, NULL, 1);
 
@@ -575,6 +592,46 @@ void snp_shutdown(void)
 }
 EXPORT_SYMBOL_FOR_MODULES(snp_shutdown, "ccp");
 
+static bool rmpopt_capable(void)
+{
+	return cpu_feature_enabled(X86_FEATURE_RMPOPT) &&
+	       cc_platform_has(CC_ATTR_HOST_SEV_SNP);
+}
+
+void snp_setup_rmpopt(void)
+{
+	u64 rmpopt_base;
+	int cpu;
+
+	if (!rmpopt_capable())
+		return;
+
+	if (!zalloc_cpumask_var(&rmpopt_cpumask, GFP_KERNEL)) {
+		pr_err("Failed to allocate RMPOPT cpumask\n");
+		return;
+	}
+
+	/*
+	 * The RMPOPT_BASE MSR is per-core, so only one thread per core needs
+	 * to set up the RMPOPT_BASE MSR.  All primary threads are online,
+	 * otherwise SNP would not have been enabled.
+	 */
+	for_each_online_cpu(cpu)
+		if (topology_is_primary_thread(cpu))
+			cpumask_set_cpu(cpu, rmpopt_cpumask);
+
+	rmpopt_pa_start = ALIGN_DOWN(PFN_PHYS(min_low_pfn), SZ_1G);
+	rmpopt_base = rmpopt_pa_start | MSR_AMD64_RMPOPT_ENABLE;
+
+	/*
+	 * Per-CPU RMPOPT tables cover at most 2 TB.  Program each core's
+	 * RMPOPT_BASE with the start of RAM to optimize up to 2 TB.
+	 */
+	for_each_cpu(cpu, rmpopt_cpumask)
+		wrmsrq_on_cpu(cpu, MSR_AMD64_RMPOPT_BASE, rmpopt_base);
+}
+EXPORT_SYMBOL_FOR_MODULES(snp_setup_rmpopt, "ccp");
+
 /*
  * Do the necessary preparations which are verified by the firmware as
  * described in the SNP_INIT_EX firmware command description in the SNP
@@ -699,13 +756,21 @@ static bool probe_segmented_rmptable_info(void)
 
 bool snp_probe_rmptable_info(void)
 {
-	if (cpu_feature_enabled(X86_FEATURE_SEGMENTED_RMP))
+	if (cpu_feature_enabled(X86_FEATURE_SEGMENTED_RMP)) {
 		rdmsrq(MSR_AMD64_RMP_CFG, rmp_cfg);
 
-	if (rmp_cfg & MSR_AMD64_SEG_RMP_ENABLED)
-		return probe_segmented_rmptable_info();
-	else
-		return probe_contiguous_rmptable_info();
+		if (rmp_cfg & MSR_AMD64_SEG_RMP_ENABLED)
+			return probe_segmented_rmptable_info();
+	}
+
+	/*
+	 * Segmented RMP is either not supported on the platform or is
+	 * disabled by the firmware.  RMPOPT is not supported without
+	 * segmented RMP.
+	 */
+	setup_clear_cpu_cap(X86_FEATURE_RMPOPT);
+
+	return probe_contiguous_rmptable_info();
 }
 
 /*
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index ca473ca198b8..da12ddf1f412 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -1510,6 +1510,8 @@ static int __sev_snp_init_locked(int *error, unsigned int max_snp_asid)
 
 	sev_es_tmr_size = SNP_TMR_SIZE;
 
+	snp_setup_rmpopt();
+
 	return 0;
 }
 
-- 
2.43.0