[PATCH v3 1/8] s390/mm: force swiotlb for protected virtualization

Michael Mueller
2019-05-29T12:27:21Z

From: Halil Pasic <pasic@linux.ibm.com>

On s390, protected virtualization guests have to use bounced I/O
buffers. That requires some plumbing.

Let us make sure, any device that uses DMA API with direct ops correctly
is spared from the problems, that a hypervisor attempting I/O to a
non-shared page would bring.

Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
---
arch/s390/Kconfig | 4 ++++
arch/s390/include/asm/mem_encrypt.h | 18 ++++++++++++++
arch/s390/mm/init.c | 47 +++++++++++++++++++++++++++++++++++++
3 files changed, 69 insertions(+)
create mode 100644 arch/s390/include/asm/mem_encrypt.h

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 109243fdb6ec..88d8355b7bf7 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -1,4 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
+config ARCH_HAS_MEM_ENCRYPT
+ def_bool y
+
config MMU
def_bool y

@@ -187,6 +190,7 @@ config S390
select VIRT_CPU_ACCOUNTING
select ARCH_HAS_SCALED_CPUTIME
select HAVE_NMI
+ select SWIOTLB

config SCHED_OMIT_FRAME_POINTER
diff --git a/arch/s390/include/asm/mem_encrypt.h b/arch/s390/include/asm/mem_encrypt.h
new file mode 100644
index 000000000000..0898c09a888c
--- /dev/null
+++ b/arch/s390/include/asm/mem_encrypt.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef S390_MEM_ENCRYPT_H__
+#define S390_MEM_ENCRYPT_H__
+
+#ifndef __ASSEMBLY__
+
+#define sme_me_mask 0ULL
+
+static inline bool sme_active(void) { return false; }
+extern bool sev_active(void);
+
+int set_memory_encrypted(unsigned long addr, int numpages);
+int set_memory_decrypted(unsigned long addr, int numpages);
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* S390_MEM_ENCRYPT_H__ */
+
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 14d1eae9fe43..f0bee6af3960 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -18,6 +18,7 @@
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
+#include <linux/swiotlb.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/pagemap.h>
@@ -29,6 +30,7 @@
#include <linux/export.h>
#include <linux/cma.h>
#include <linux/gfp.h>
+#include <linux/dma-mapping.h>
#include <asm/processor.h>
#include <linux/uaccess.h>
#include <asm/pgtable.h>
@@ -42,6 +44,8 @@
#include <asm/sclp.h>
#include <asm/set_memory.h>
#include <asm/kasan.h>
+#include <asm/dma-mapping.h>
+#include <asm/uv.h>

pgd_t swapper_pg_dir[PTRS_PER_PGD] __section(.bss..swapper_pg_dir);

@@ -128,6 +132,47 @@ void mark_rodata_ro(void)
pr_info("Write protected read-only-after-init data: %luk\n", size >> 10);
}

+int set_memory_encrypted(unsigned long addr, int numpages)
+{
+ int i;
+
+ /* make specified pages unshared, (swiotlb, dma_free) */
+ for (i = 0; i < numpages; ++i) {
+ uv_remove_shared(addr);
+ addr += PAGE_SIZE;
+ }
+ return 0;
+}
+
+int set_memory_decrypted(unsigned long addr, int numpages)
+{
+ int i;
+ /* make specified pages shared (swiotlb, dma_alloca) */
+ for (i = 0; i < numpages; ++i) {
+ uv_set_shared(addr);
+ addr += PAGE_SIZE;
+ }
+ return 0;
+}
+
+/* are we a protected virtualization guest? */
+bool sev_active(void)
+{
+ return is_prot_virt_guest();
+}
+
+/* protected virtualization */
+static void pv_init(void)
+{
+ if (!is_prot_virt_guest())
+ return;
+
+ /* make sure bounce buffers are shared */
+ swiotlb_init(1);
+ swiotlb_update_mem_attributes();
+ swiotlb_force = SWIOTLB_FORCE;
+}
+
void __init mem_init(void)
{
cpumask_set_cpu(0, &init_mm.context.cpu_attach_mask);
@@ -136,6 +181,8 @@ void __init mem_init(void)
set_max_mapnr(max_low_pfn);
high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);

+ pv_init();
+
/* Setup guest page hinting */
cmma_init();

--
2.13.4