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Subject[PATCH 07/12] powerpc/pseries/svm: Use shared memory for Debug Trace Log (DTL)
Date
From: Anshuman Khandual <khandual@linux.vnet.ibm.com>

Secure guests need to share the DTL buffers with the hypervisor. To that
end, use a kmem_cache constructor which converts the underlying buddy
allocated SLUB cache pages into shared memory.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
---
arch/powerpc/include/asm/svm.h | 5 ++++
arch/powerpc/platforms/pseries/Makefile | 1 +
arch/powerpc/platforms/pseries/setup.c | 5 +++-
arch/powerpc/platforms/pseries/svm.c | 40 +++++++++++++++++++++++++
4 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/svm.h b/arch/powerpc/include/asm/svm.h
index fef3740f46a6..f253116c31fc 100644
--- a/arch/powerpc/include/asm/svm.h
+++ b/arch/powerpc/include/asm/svm.h
@@ -15,6 +15,9 @@ static inline bool is_secure_guest(void)
return mfmsr() & MSR_S;
}

+void dtl_cache_ctor(void *addr);
+#define get_dtl_cache_ctor() (is_secure_guest() ? dtl_cache_ctor : NULL)
+
#else /* CONFIG_PPC_SVM */

static inline bool is_secure_guest(void)
@@ -22,5 +25,7 @@ static inline bool is_secure_guest(void)
return false;
}

+#define get_dtl_cache_ctor() NULL
+
#endif /* CONFIG_PPC_SVM */
#endif /* _ASM_POWERPC_SVM_H */
diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index a43ec843c8e2..b7b6e6f52bd0 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_LPARCFG) += lparcfg.o
obj-$(CONFIG_IBMVIO) += vio.o
obj-$(CONFIG_IBMEBUS) += ibmebus.o
obj-$(CONFIG_PAPR_SCM) += papr_scm.o
+obj-$(CONFIG_PPC_SVM) += svm.o

ifdef CONFIG_PPC_PSERIES
obj-$(CONFIG_SUSPEND) += suspend.o
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index e4f0dfd4ae33..c928e6e8a279 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -71,6 +71,7 @@
#include <asm/isa-bridge.h>
#include <asm/security_features.h>
#include <asm/asm-const.h>
+#include <asm/svm.h>

#include "pseries.h"
#include "../../../../drivers/pci/pci.h"
@@ -329,8 +330,10 @@ static inline int alloc_dispatch_logs(void)

static int alloc_dispatch_log_kmem_cache(void)
{
+ void (*ctor)(void *) = get_dtl_cache_ctor();
+
dtl_cache = kmem_cache_create("dtl", DISPATCH_LOG_BYTES,
- DISPATCH_LOG_BYTES, 0, NULL);
+ DISPATCH_LOG_BYTES, 0, ctor);
if (!dtl_cache) {
pr_warn("Failed to create dispatch trace log buffer cache\n");
pr_warn("Stolen time statistics will be unreliable\n");
diff --git a/arch/powerpc/platforms/pseries/svm.c b/arch/powerpc/platforms/pseries/svm.c
new file mode 100644
index 000000000000..c508196f7c83
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/svm.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Secure VM platform
+ *
+ * Copyright 2019 IBM Corporation
+ * Author: Anshuman Khandual <khandual@linux.vnet.ibm.com>
+ */
+
+#include <linux/mm.h>
+#include <asm/ultravisor.h>
+
+/* There's one dispatch log per CPU. */
+#define NR_DTL_PAGE (DISPATCH_LOG_BYTES * CONFIG_NR_CPUS / PAGE_SIZE)
+
+static struct page *dtl_page_store[NR_DTL_PAGE];
+static long dtl_nr_pages;
+
+static bool is_dtl_page_shared(struct page *page)
+{
+ long i;
+
+ for (i = 0; i < dtl_nr_pages; i++)
+ if (dtl_page_store[i] == page)
+ return true;
+
+ return false;
+}
+
+void dtl_cache_ctor(void *addr)
+{
+ unsigned long pfn = PHYS_PFN(__pa(addr));
+ struct page *page = pfn_to_page(pfn);
+
+ if (!is_dtl_page_shared(page)) {
+ dtl_page_store[dtl_nr_pages] = page;
+ dtl_nr_pages++;
+ WARN_ON(dtl_nr_pages >= NR_DTL_PAGE);
+ uv_share_page(pfn, 1);
+ }
+}
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