From: Thiago Jung Bauermann <bauerman@linux.ibm.com>
To: iommu@lists.linux-foundation.org
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
linuxppc-dev@lists.ozlabs.org, Ram Pai <linuxram@us.ibm.com>,
linux-kernel@vger.kernel.org,
Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
Robin Murphy <robin.murphy@arm.com>,
Christoph Hellwig <hch@lst.de>
Subject: [PATCH v3] powerpc/pseries/svm: Allocate SWIOTLB buffer anywhere in memory
Date: Tue, 18 Aug 2020 19:11:26 -0300 [thread overview]
Message-ID: <20200818221126.391073-1-bauerman@linux.ibm.com> (raw)
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().
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
---
arch/powerpc/include/asm/svm.h | 4 ++++
arch/powerpc/mm/mem.c | 6 +++++-
arch/powerpc/platforms/pseries/svm.c | 26 ++++++++++++++++++++++++++
3 files changed, 35 insertions(+), 1 deletion(-)
Changes from v2:
- Panic if unable to allocate buffer, as suggested by Christoph.
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..81085eb8f225 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 +35,31 @@ 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));
+ panic("SVM: Cannot allocate SWIOTLB buffer");
+}
+
int set_memory_encrypted(unsigned long addr, int numpages)
{
if (!PAGE_ALIGNED(addr))
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next reply other threads:[~2020-08-18 22:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-18 22:11 Thiago Jung Bauermann [this message]
2020-08-19 4:43 ` [PATCH v3] powerpc/pseries/svm: Allocate SWIOTLB buffer anywhere in memory Christoph Hellwig
2020-08-19 16:50 ` Thiago Jung Bauermann
2020-08-20 2:12 ` Michael Ellerman
2020-08-19 17:00 ` Konrad Rzeszutek Wilk
2020-08-19 19:48 ` Thiago Jung Bauermann
2020-09-17 11:27 ` Michael Ellerman
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