[PATCH 10/15] swiotlb: add a SWIOTLB_ANY flag to lift the low memory restriction

[Christoph Hellwig <hch@xxxxxx>]

Power SVM wants to allocate a swiotlb buffer that is not restricted to
low memory for the trusted hypervisor scheme.  Consolidate the support
for this into the swiotlb_init interface by adding a new flag.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 arch/powerpc/include/asm/svm.h       |  4 ----
 arch/powerpc/include/asm/swiotlb.h   |  1 +
 arch/powerpc/kernel/dma-swiotlb.c    |  1 +
 arch/powerpc/mm/mem.c                |  5 +----
 arch/powerpc/platforms/pseries/svm.c | 26 +-------------------------
 include/linux/swiotlb.h              |  1 +
 kernel/dma/swiotlb.c                 | 11 +++++++++--
 7 files changed, 14 insertions(+), 35 deletions(-)

diff --git a/arch/powerpc/include/asm/svm.h b/arch/powerpc/include/asm/svm.h
index 7546402d796af..85580b30aba48 100644
--- a/arch/powerpc/include/asm/svm.h
+++ b/arch/powerpc/include/asm/svm.h
@@ -15,8 +15,6 @@ 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)
 
@@ -27,8 +25,6 @@ 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/include/asm/swiotlb.h 
b/arch/powerpc/include/asm/swiotlb.h
index 3c1a1cd161286..4203b5e0a88ed 100644
--- a/arch/powerpc/include/asm/swiotlb.h
+++ b/arch/powerpc/include/asm/swiotlb.h
@@ -9,6 +9,7 @@
 #include <linux/swiotlb.h>
 
 extern unsigned int ppc_swiotlb_enable;
+extern unsigned int ppc_swiotlb_flags;
 
 #ifdef CONFIG_SWIOTLB
 void swiotlb_detect_4g(void);
diff --git a/arch/powerpc/kernel/dma-swiotlb.c 
b/arch/powerpc/kernel/dma-swiotlb.c
index fc7816126a401..ba256c37bcc0f 100644
--- a/arch/powerpc/kernel/dma-swiotlb.c
+++ b/arch/powerpc/kernel/dma-swiotlb.c
@@ -10,6 +10,7 @@
 #include <asm/swiotlb.h>
 
 unsigned int ppc_swiotlb_enable;
+unsigned int ppc_swiotlb_flags;
 
 void __init swiotlb_detect_4g(void)
 {
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index e1519e2edc656..a4d65418c30a9 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -249,10 +249,7 @@ void __init mem_init(void)
         * back to to-down.
         */
        memblock_set_bottom_up(true);
-       if (is_secure_guest())
-               svm_swiotlb_init();
-       else
-               swiotlb_init(ppc_swiotlb_enable, 0);
+       swiotlb_init(ppc_swiotlb_enable, ppc_swiotlb_flags);
 #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 c5228f4969eb2..3b4045d508ec8 100644
--- a/arch/powerpc/platforms/pseries/svm.c
+++ b/arch/powerpc/platforms/pseries/svm.c
@@ -28,7 +28,7 @@ static int __init init_svm(void)
         * need to use the SWIOTLB buffer for DMA even if dma_capable() says
         * otherwise.
         */
-       swiotlb_force = SWIOTLB_FORCE;
+       ppc_swiotlb_flags |= SWIOTLB_ANY | SWIOTLB_FORCE;
 
        /* Share the SWIOTLB buffer with the host. */
        swiotlb_update_mem_attributes();
@@ -37,30 +37,6 @@ 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;
-
-
-       memblock_free(vstart, PAGE_ALIGN(io_tlb_nslabs << IO_TLB_SHIFT));
-       panic("SVM: Cannot allocate SWIOTLB buffer");
-}
-
 int set_memory_encrypted(unsigned long addr, int numpages)
 {
        if (!cc_platform_has(CC_ATTR_MEM_ENCRYPT))
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index ae0407173e845..eabdd89987027 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -15,6 +15,7 @@ struct scatterlist;
 
 #define SWIOTLB_VERBOSE        (1 << 0) /* verbose initialization */
 #define SWIOTLB_FORCE  (1 << 1) /* force bounce buffering */
+#define SWIOTLB_ANY    (1 << 2) /* allow any memory for the buffer */
 
 /*
  * Maximum allowable number of contiguous slabs to map,
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 86e877a96b828..f6e091424af3d 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -266,8 +266,15 @@ void __init swiotlb_init(bool addressing_limit, unsigned 
int flags)
        if (swiotlb_force_disable)
                return;
 
-       /* Get IO TLB memory from the low pages */
-       tlb = memblock_alloc_low(bytes, PAGE_SIZE);
+       /*
+        * By default allocate the bounce buffer memory from low memory, but
+        * allow to pick a location everywhere for hypervisors with guest
+        * memory encryption.
+        */
+       if (flags & SWIOTLB_ANY)
+               tlb = memblock_alloc(bytes, PAGE_SIZE);
+       else
+               tlb = memblock_alloc_low(bytes, PAGE_SIZE);
        if (!tlb)
                goto fail;
        if (swiotlb_init_with_tbl(tlb, default_nslabs, flags))
-- 
2.30.2