| Message ID | 20240819131924.372366-15-steven.price@arm.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | arm64: Support for running as a guest in Arm CCA | expand |
On Mon, Aug 19, 2024 at 02:19:19PM +0100, Steven Price wrote: > Within a realm guest it's not possible for a device emulated by the VMM > to access arbitrary guest memory. So force the use of bounce buffers to > ensure that the memory the emulated devices are accessing is in memory > which is explicitly shared with the host. > > This adds a call to swiotlb_update_mem_attributes() which calls > set_memory_decrypted() to ensure the bounce buffer memory is shared with > the host. For non-realm guests or hosts this is a no-op. > > Co-developed-by: Suzuki K Poulose <suzuki.poulose@arm.com> > Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> > Signed-off-by: Steven Price <steven.price@arm.com> > --- > v3: Simplify mem_init() by using a 'flags' variable. > --- > arch/arm64/kernel/rsi.c | 1 + > arch/arm64/mm/init.c | 10 +++++++++- > 2 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c > index 5c2c977a50fb..69d8d9791c65 100644 > --- a/arch/arm64/kernel/rsi.c > +++ b/arch/arm64/kernel/rsi.c > @@ -6,6 +6,7 @@ > #include <linux/jump_label.h> > #include <linux/memblock.h> > #include <linux/psci.h> > +#include <linux/swiotlb.h> > > #include <asm/io.h> > #include <asm/rsi.h> > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 9b5ab6818f7f..1d595b63da71 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -41,6 +41,7 @@ > #include <asm/kvm_host.h> > #include <asm/memory.h> > #include <asm/numa.h> > +#include <asm/rsi.h> > #include <asm/sections.h> > #include <asm/setup.h> > #include <linux/sizes.h> > @@ -369,8 +370,14 @@ void __init bootmem_init(void) > */ > void __init mem_init(void) > { > + unsigned int flags = SWIOTLB_VERBOSE; > bool swiotlb = max_pfn > PFN_DOWN(arm64_dma_phys_limit); > > + if (is_realm_world()) { > + swiotlb = true; > + flags |= SWIOTLB_FORCE; > + } > + > if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb) { > /* > * If no bouncing needed for ZONE_DMA, reduce the swiotlb > @@ -382,7 +389,8 @@ void __init mem_init(void) > swiotlb = true; > } > > - swiotlb_init(swiotlb, SWIOTLB_VERBOSE); > + swiotlb_init(swiotlb, flags); > + swiotlb_update_mem_attributes(); IIRC Will mentioned on a previous version of this series: what do we do with the kmalloc() minalign bouncing (or other bouncing)? I think this would only work if the device is shared. I'm more and more inclined to only support shared devices with this series (no dev assignment) and make it a strict dependence on RMM 1.0. Running it in a different configuration with private devices will fall apart. With this condition, the patch looks fine: Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c index 5c2c977a50fb..69d8d9791c65 100644 --- a/arch/arm64/kernel/rsi.c +++ b/arch/arm64/kernel/rsi.c @@ -6,6 +6,7 @@ #include <linux/jump_label.h> #include <linux/memblock.h> #include <linux/psci.h> +#include <linux/swiotlb.h> #include <asm/io.h> #include <asm/rsi.h> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 9b5ab6818f7f..1d595b63da71 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -41,6 +41,7 @@ #include <asm/kvm_host.h> #include <asm/memory.h> #include <asm/numa.h> +#include <asm/rsi.h> #include <asm/sections.h> #include <asm/setup.h> #include <linux/sizes.h> @@ -369,8 +370,14 @@ void __init bootmem_init(void) */ void __init mem_init(void) { + unsigned int flags = SWIOTLB_VERBOSE; bool swiotlb = max_pfn > PFN_DOWN(arm64_dma_phys_limit); + if (is_realm_world()) { + swiotlb = true; + flags |= SWIOTLB_FORCE; + } + if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb) { /* * If no bouncing needed for ZONE_DMA, reduce the swiotlb @@ -382,7 +389,8 @@ void __init mem_init(void) swiotlb = true; } - swiotlb_init(swiotlb, SWIOTLB_VERBOSE); + swiotlb_init(swiotlb, flags); + swiotlb_update_mem_attributes(); /* this will put all unused low memory onto the freelists */ memblock_free_all();