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Message-Id: <20200817214658.103093-1-bauerman@linux.ibm.com>
Date: Mon, 17 Aug 2020 18:46:58 -0300
From: Thiago Jung Bauermann <bauerman@...ux.ibm.com>
To: iommu@...ts.linux-foundation.org
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
Christoph Hellwig <hch@....de>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Robin Murphy <robin.murphy@....com>,
Michael Ellerman <mpe@...erman.id.au>,
Ram Pai <linuxram@...ibm.com>,
Satheesh Rajendran <sathnaga@...ux.vnet.ibm.com>,
Thiago Jung Bauermann <bauerman@...ux.ibm.com>
Subject: [PATCH v2] powerpc/pseries/svm: Allocate SWIOTLB buffer anywhere in memory
POWER secure guests (i.e., guests which use the Protection Execution
Facility) need to use SWIOTLB to be able to do I/O with the hypervisor, but
they don't need the SWIOTLB memory to be in low addresses since the
hypervisor doesn't have any addressing limitation.
This solves a SWIOTLB initialization problem we are seeing in secure guests
with 128 GB of RAM: they are configured with 4 GB of crashkernel reserved
memory, which leaves no space for SWIOTLB in low addresses.
To do this, we use mostly the same code as swiotlb_init(), but allocate the
buffer using memblock_alloc() instead of memblock_alloc_low().
We also need to add swiotlb_set_no_iotlb_memory() in order to set the
no_iotlb_memory flag if initialization fails.
Signed-off-by: Thiago Jung Bauermann <bauerman@...ux.ibm.com>
---
arch/powerpc/include/asm/svm.h | 4 ++++
arch/powerpc/mm/mem.c | 6 +++++-
arch/powerpc/platforms/pseries/svm.c | 27 +++++++++++++++++++++++++++
include/linux/swiotlb.h | 1 +
kernel/dma/swiotlb.c | 5 +++++
5 files changed, 42 insertions(+), 1 deletion(-)
Changes from v1:
- Open-code swiotlb_init() in arch-specific code, as suggested by
Christoph.
diff --git a/arch/powerpc/include/asm/svm.h b/arch/powerpc/include/asm/svm.h
index 85580b30aba4..7546402d796a 100644
--- a/arch/powerpc/include/asm/svm.h
+++ b/arch/powerpc/include/asm/svm.h
@@ -15,6 +15,8 @@ static inline bool is_secure_guest(void)
return mfmsr() & MSR_S;
}
+void __init svm_swiotlb_init(void);
+
void dtl_cache_ctor(void *addr);
#define get_dtl_cache_ctor() (is_secure_guest() ? dtl_cache_ctor : NULL)
@@ -25,6 +27,8 @@ static inline bool is_secure_guest(void)
return false;
}
+static inline void svm_swiotlb_init(void) {}
+
#define get_dtl_cache_ctor() NULL
#endif /* CONFIG_PPC_SVM */
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index c2c11eb8dcfc..0f21bcb16405 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -50,6 +50,7 @@
#include <asm/swiotlb.h>
#include <asm/rtas.h>
#include <asm/kasan.h>
+#include <asm/svm.h>
#include <mm/mmu_decl.h>
@@ -290,7 +291,10 @@ void __init mem_init(void)
* back to to-down.
*/
memblock_set_bottom_up(true);
- swiotlb_init(0);
+ if (is_secure_guest())
+ svm_swiotlb_init();
+ else
+ swiotlb_init(0);
#endif
high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
diff --git a/arch/powerpc/platforms/pseries/svm.c b/arch/powerpc/platforms/pseries/svm.c
index 40c0637203d5..d592e663a8d6 100644
--- a/arch/powerpc/platforms/pseries/svm.c
+++ b/arch/powerpc/platforms/pseries/svm.c
@@ -7,6 +7,7 @@
*/
#include <linux/mm.h>
+#include <linux/memblock.h>
#include <asm/machdep.h>
#include <asm/svm.h>
#include <asm/swiotlb.h>
@@ -34,6 +35,32 @@ static int __init init_svm(void)
}
machine_early_initcall(pseries, init_svm);
+/*
+ * Initialize SWIOTLB. Essentially the same as swiotlb_init(), except that it
+ * can allocate the buffer anywhere in memory. Since the hypervisor doesn't have
+ * any addressing limitation, we don't need to allocate it in low addresses.
+ */
+void __init svm_swiotlb_init(void)
+{
+ unsigned char *vstart;
+ unsigned long bytes, io_tlb_nslabs;
+
+ io_tlb_nslabs = (swiotlb_size_or_default() >> IO_TLB_SHIFT);
+ io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE);
+
+ bytes = io_tlb_nslabs << IO_TLB_SHIFT;
+
+ vstart = memblock_alloc(PAGE_ALIGN(bytes), PAGE_SIZE);
+ if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, false))
+ return;
+
+ if (io_tlb_start)
+ memblock_free_early(io_tlb_start,
+ PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
+ pr_warn("Cannot allocate SWIOTLB buffer");
+ swiotlb_set_no_iotlb_memory(true);
+}
+
int set_memory_encrypted(unsigned long addr, int numpages)
{
if (!PAGE_ALIGNED(addr))
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 046bb94bd4d6..991e9f13e663 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -35,6 +35,7 @@ extern unsigned long swiotlb_nr_tbl(void);
unsigned long swiotlb_size_or_default(void);
extern int swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs);
extern void __init swiotlb_update_mem_attributes(void);
+void __init swiotlb_set_no_iotlb_memory(bool value);
/*
* Enumeration for sync targets
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index c19379fabd20..ed2b8818ff67 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -132,6 +132,11 @@ early_param("swiotlb", setup_io_tlb_npages);
static bool no_iotlb_memory;
+void __init swiotlb_set_no_iotlb_memory(bool value)
+{
+ no_iotlb_memory = value;
+}
+
unsigned long swiotlb_nr_tbl(void)
{
return unlikely(no_iotlb_memory) ? 0 : io_tlb_nslabs;
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