[PATCH v2 0/2] irqchip/gic-v3-its: Mark ITS tables as decrypted

[PATCH v2 0/2] irqchip/gic-v3-its: Mark ITS tables as decrypted

[Steven Price]

These two patches were taken from the larger series to support running
Linux as a realm guest in CCA[1]. They add support to the GIC for
allocating the ITS pages such that they are decrypted so that the host
can access then for emulation purposes.

Note that there are likely to be future changes to make this more
configurable in the future, as it's possible that in a future
configuration a protected component within the realm could take on the
emulation responsibilities ('Planes support')[2]. But this is a good
building block for the future.

[1] https://lore.kernel.org/r/20240819131924.372366-1-steven.price%40arm.com
[2] https://lore.kernel.org/r/beff9162-e1ba-4f72-91ea-329eaed48dbc%40arm.com

Steven Price (2):
  irqchip/gic-v3-its: Share ITS tables with a non-trusted hypervisor
  irqchip/gic-v3-its: Rely on genpool alignment

 drivers/irqchip/irq-gic-v3-its.c | 154 ++++++++++++++++++++++++++-----
 1 file changed, 129 insertions(+), 25 deletions(-)

-- 
2.34.1

[PATCH v2 1/2] irqchip/gic-v3-its: Share ITS tables with a non-trusted hypervisor

[Steven Price]

Within a realm guest the ITS is emulated by the host. This means the
allocations must have been made available to the host by a call to
set_memory_decrypted(). Introduce an allocation function which performs
this extra call.

For the ITT use a custom genpool-based allocator that calls
set_memory_decrypted() for each page allocated, but then suballocates
the size needed for each ITT. Note that there is no mechanism
implemented to return pages from the genpool, but it is unlikely the
peak number of devices will so much larger than the normal level - so
this isn't expected to be an issue.

Co-developed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Tested-by: Will Deacon <will@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Steven Price <steven.price@arm.com>
---
Changes since v1:
 * Drop WARN_ONs and add a comment explaining that, if they fail,
   set_memory_{en,de}crypted() will already have WARNed and that we are
   purposefully leaking memory in those cases.
---
 drivers/irqchip/irq-gic-v3-its.c | 151 ++++++++++++++++++++++++++-----
 1 file changed, 128 insertions(+), 23 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index fdec478ba5e7..7a62fd3a8673 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -12,12 +12,14 @@
 #include <linux/crash_dump.h>
 #include <linux/delay.h>
 #include <linux/efi.h>
+#include <linux/genalloc.h>
 #include <linux/interrupt.h>
 #include <linux/iommu.h>
 #include <linux/iopoll.h>
 #include <linux/irqdomain.h>
 #include <linux/list.h>
 #include <linux/log2.h>
+#include <linux/mem_encrypt.h>
 #include <linux/memblock.h>
 #include <linux/mm.h>
 #include <linux/msi.h>
@@ -27,6 +29,7 @@
 #include <linux/of_pci.h>
 #include <linux/of_platform.h>
 #include <linux/percpu.h>
+#include <linux/set_memory.h>
 #include <linux/slab.h>
 #include <linux/syscore_ops.h>
 
@@ -164,6 +167,7 @@ struct its_device {
 	struct its_node		*its;
 	struct event_lpi_map	event_map;
 	void			*itt;
+	u32			itt_sz;
 	u32			nr_ites;
 	u32			device_id;
 	bool			shared;
@@ -199,6 +203,93 @@ static DEFINE_IDA(its_vpeid_ida);
 #define gic_data_rdist_rd_base()	(gic_data_rdist()->rd_base)
 #define gic_data_rdist_vlpi_base()	(gic_data_rdist_rd_base() + SZ_128K)
 
+static struct page *its_alloc_pages_node(int node, gfp_t gfp,
+					 unsigned int order)
+{
+	struct page *page;
+	int ret = 0;
+
+	page = alloc_pages_node(node, gfp, order);
+
+	if (!page)
+		return NULL;
+
+	ret = set_memory_decrypted((unsigned long)page_address(page),
+				   1 << order);
+	/*
+	 * If set_memory_decrypted() fails then we don't know what state the
+	 * page is in, so we can't free it. Instead we leak it.
+	 * set_memory_decrypted() will already have WARNed.
+	 */
+	if (ret)
+		return NULL;
+
+	return page;
+}
+
+static struct page *its_alloc_pages(gfp_t gfp, unsigned int order)
+{
+	return its_alloc_pages_node(NUMA_NO_NODE, gfp, order);
+}
+
+static void its_free_pages(void *addr, unsigned int order)
+{
+	/*
+	 * If the memory cannot be encrypted again then we must leak the pages.
+	 * set_memory_encrypted will already have WARNed.
+	 */
+	if (set_memory_encrypted((unsigned long)addr, 1 << order))
+		return;
+	free_pages((unsigned long)addr, order);
+}
+
+static struct gen_pool *itt_pool;
+
+static void *itt_alloc_pool(int node, int size)
+{
+	unsigned long addr;
+	struct page *page;
+
+	if (size >= PAGE_SIZE) {
+		page = its_alloc_pages_node(node,
+					    GFP_KERNEL | __GFP_ZERO,
+					    get_order(size));
+
+		if (!page)
+			return NULL;
+
+		return page_address(page);
+	}
+
+	do {
+		addr = gen_pool_alloc(itt_pool, size);
+		if (addr)
+			break;
+
+		page = its_alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 1);
+		if (!page)
+			break;
+
+		gen_pool_add(itt_pool, (unsigned long)page_address(page),
+			     PAGE_SIZE, node);
+	} while (!addr);
+
+	return (void *)addr;
+}
+
+static void itt_free_pool(void *addr, int size)
+{
+	if (!addr)
+		return;
+
+	if (size >= PAGE_SIZE) {
+		its_free_pages(addr, get_order(size));
+		return;
+	}
+
+	gen_pool_free(itt_pool, (unsigned long)addr, size);
+}
+
 /*
  * Skip ITSs that have no vLPIs mapped, unless we're on GICv4.1, as we
  * always have vSGIs mapped.
@@ -2181,7 +2272,8 @@ static struct page *its_allocate_prop_table(gfp_t gfp_flags)
 {
 	struct page *prop_page;
 
-	prop_page = alloc_pages(gfp_flags, get_order(LPI_PROPBASE_SZ));
+	prop_page = its_alloc_pages(gfp_flags,
+				    get_order(LPI_PROPBASE_SZ));
 	if (!prop_page)
 		return NULL;
 
@@ -2192,8 +2284,8 @@ static struct page *its_allocate_prop_table(gfp_t gfp_flags)
 
 static void its_free_prop_table(struct page *prop_page)
 {
-	free_pages((unsigned long)page_address(prop_page),
-		   get_order(LPI_PROPBASE_SZ));
+	its_free_pages(page_address(prop_page),
+		       get_order(LPI_PROPBASE_SZ));
 }
 
 static bool gic_check_reserved_range(phys_addr_t addr, unsigned long size)
@@ -2315,7 +2407,8 @@ static int its_setup_baser(struct its_node *its, struct its_baser *baser,
 		order = get_order(GITS_BASER_PAGES_MAX * psz);
 	}
 
-	page = alloc_pages_node(its->numa_node, GFP_KERNEL | __GFP_ZERO, order);
+	page = its_alloc_pages_node(its->numa_node,
+				    GFP_KERNEL | __GFP_ZERO, order);
 	if (!page)
 		return -ENOMEM;
 
@@ -2328,7 +2421,7 @@ static int its_setup_baser(struct its_node *its, struct its_baser *baser,
 		/* 52bit PA is supported only when PageSize=64K */
 		if (psz != SZ_64K) {
 			pr_err("ITS: no 52bit PA support when psz=%d\n", psz);
-			free_pages((unsigned long)base, order);
+			its_free_pages(base, order);
 			return -ENXIO;
 		}
 
@@ -2384,7 +2477,7 @@ static int its_setup_baser(struct its_node *its, struct its_baser *baser,
 		pr_err("ITS@%pa: %s doesn't stick: %llx %llx\n",
 		       &its->phys_base, its_base_type_string[type],
 		       val, tmp);
-		free_pages((unsigned long)base, order);
+		its_free_pages(base, order);
 		return -ENXIO;
 	}
 
@@ -2523,8 +2616,8 @@ static void its_free_tables(struct its_node *its)
 
 	for (i = 0; i < GITS_BASER_NR_REGS; i++) {
 		if (its->tables[i].base) {
-			free_pages((unsigned long)its->tables[i].base,
-				   its->tables[i].order);
+			its_free_pages(its->tables[i].base,
+				       its->tables[i].order);
 			its->tables[i].base = NULL;
 		}
 	}
@@ -2790,7 +2883,8 @@ static bool allocate_vpe_l2_table(int cpu, u32 id)
 
 	/* Allocate memory for 2nd level table */
 	if (!table[idx]) {
-		page = alloc_pages(GFP_KERNEL | __GFP_ZERO, get_order(psz));
+		page = its_alloc_pages(GFP_KERNEL | __GFP_ZERO,
+				       get_order(psz));
 		if (!page)
 			return false;
 
@@ -2909,7 +3003,8 @@ static int allocate_vpe_l1_table(void)
 
 	pr_debug("np = %d, npg = %lld, psz = %d, epp = %d, esz = %d\n",
 		 np, npg, psz, epp, esz);
-	page = alloc_pages(GFP_ATOMIC | __GFP_ZERO, get_order(np * PAGE_SIZE));
+	page = its_alloc_pages(GFP_ATOMIC | __GFP_ZERO,
+			       get_order(np * PAGE_SIZE));
 	if (!page)
 		return -ENOMEM;
 
@@ -2955,8 +3050,8 @@ static struct page *its_allocate_pending_table(gfp_t gfp_flags)
 {
 	struct page *pend_page;
 
-	pend_page = alloc_pages(gfp_flags | __GFP_ZERO,
-				get_order(LPI_PENDBASE_SZ));
+	pend_page = its_alloc_pages(gfp_flags | __GFP_ZERO,
+				    get_order(LPI_PENDBASE_SZ));
 	if (!pend_page)
 		return NULL;
 
@@ -2968,7 +3063,7 @@ static struct page *its_allocate_pending_table(gfp_t gfp_flags)
 
 static void its_free_pending_table(struct page *pt)
 {
-	free_pages((unsigned long)page_address(pt), get_order(LPI_PENDBASE_SZ));
+	its_free_pages(page_address(pt), get_order(LPI_PENDBASE_SZ));
 }
 
 /*
@@ -3303,8 +3398,9 @@ static bool its_alloc_table_entry(struct its_node *its,
 
 	/* Allocate memory for 2nd level table */
 	if (!table[idx]) {
-		page = alloc_pages_node(its->numa_node, GFP_KERNEL | __GFP_ZERO,
-					get_order(baser->psz));
+		page = its_alloc_pages_node(its->numa_node,
+					    GFP_KERNEL | __GFP_ZERO,
+					    get_order(baser->psz));
 		if (!page)
 			return false;
 
@@ -3399,7 +3495,6 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
 	if (WARN_ON(!is_power_of_2(nvecs)))
 		nvecs = roundup_pow_of_two(nvecs);
 
-	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 	/*
 	 * Even if the device wants a single LPI, the ITT must be
 	 * sized as a power of two (and you need at least one bit...).
@@ -3407,7 +3502,11 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
 	nr_ites = max(2, nvecs);
 	sz = nr_ites * (FIELD_GET(GITS_TYPER_ITT_ENTRY_SIZE, its->typer) + 1);
 	sz = max(sz, ITS_ITT_ALIGN) + ITS_ITT_ALIGN - 1;
-	itt = kzalloc_node(sz, GFP_KERNEL, its->numa_node);
+
+	itt = itt_alloc_pool(its->numa_node, sz);
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+
 	if (alloc_lpis) {
 		lpi_map = its_lpi_alloc(nvecs, &lpi_base, &nr_lpis);
 		if (lpi_map)
@@ -3419,9 +3518,9 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
 		lpi_base = 0;
 	}
 
-	if (!dev || !itt ||  !col_map || (!lpi_map && alloc_lpis)) {
+	if (!dev || !itt || !col_map || (!lpi_map && alloc_lpis)) {
 		kfree(dev);
-		kfree(itt);
+		itt_free_pool(itt, sz);
 		bitmap_free(lpi_map);
 		kfree(col_map);
 		return NULL;
@@ -3431,6 +3530,7 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
 
 	dev->its = its;
 	dev->itt = itt;
+	dev->itt_sz = sz;
 	dev->nr_ites = nr_ites;
 	dev->event_map.lpi_map = lpi_map;
 	dev->event_map.col_map = col_map;
@@ -3458,7 +3558,7 @@ static void its_free_device(struct its_device *its_dev)
 	list_del(&its_dev->entry);
 	raw_spin_unlock_irqrestore(&its_dev->its->lock, flags);
 	kfree(its_dev->event_map.col_map);
-	kfree(its_dev->itt);
+	itt_free_pool(its_dev->itt, its_dev->itt_sz);
 	kfree(its_dev);
 }
 
@@ -5116,8 +5216,9 @@ static int __init its_probe_one(struct its_node *its)
 		}
 	}
 
-	page = alloc_pages_node(its->numa_node, GFP_KERNEL | __GFP_ZERO,
-				get_order(ITS_CMD_QUEUE_SZ));
+	page = its_alloc_pages_node(its->numa_node,
+				    GFP_KERNEL | __GFP_ZERO,
+				    get_order(ITS_CMD_QUEUE_SZ));
 	if (!page) {
 		err = -ENOMEM;
 		goto out_unmap_sgir;
@@ -5181,7 +5282,7 @@ static int __init its_probe_one(struct its_node *its)
 out_free_tables:
 	its_free_tables(its);
 out_free_cmd:
-	free_pages((unsigned long)its->cmd_base, get_order(ITS_CMD_QUEUE_SZ));
+	its_free_pages(its->cmd_base, get_order(ITS_CMD_QUEUE_SZ));
 out_unmap_sgir:
 	if (its->sgir_base)
 		iounmap(its->sgir_base);
@@ -5667,6 +5768,10 @@ int __init its_init(struct fwnode_handle *handle, struct rdists *rdists,
 	bool has_v4_1 = false;
 	int err;
 
+	itt_pool = gen_pool_create(get_order(ITS_ITT_ALIGN), -1);
+	if (!itt_pool)
+		return -ENOMEM;
+
 	gic_rdists = rdists;
 
 	lpi_prop_prio = irq_prio;
-- 
2.34.1

[PATCH v2 2/2] irqchip/gic-v3-its: Rely on genpool alignment

[Steven Price]

its_create_device() over-allocated by ITS_ITT_ALIGN - 1 bytes to ensure
that an aligned area was available within the allocation. The new
genpool allocator has its min_alloc_order set to
get_order(ITS_ITT_ALIGN) so all allocations from it should be
appropriately aligned.

Remove the over-allocation from its_create_device() and alignment from
its_build_mapd_cmd().

Tested-by: Will Deacon <will@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 drivers/irqchip/irq-gic-v3-its.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 7a62fd3a8673..1d2a952e342d 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -712,7 +712,6 @@ static struct its_collection *its_build_mapd_cmd(struct its_node *its,
 	u8 size = ilog2(desc->its_mapd_cmd.dev->nr_ites);
 
 	itt_addr = virt_to_phys(desc->its_mapd_cmd.dev->itt);
-	itt_addr = ALIGN(itt_addr, ITS_ITT_ALIGN);
 
 	its_encode_cmd(cmd, GITS_CMD_MAPD);
 	its_encode_devid(cmd, desc->its_mapd_cmd.dev->device_id);
@@ -3501,7 +3500,7 @@ static struct its_device *its_create_device(struct its_node *its, u32 dev_id,
 	 */
 	nr_ites = max(2, nvecs);
 	sz = nr_ites * (FIELD_GET(GITS_TYPER_ITT_ENTRY_SIZE, its->typer) + 1);
-	sz = max(sz, ITS_ITT_ALIGN) + ITS_ITT_ALIGN - 1;
+	sz = max(sz, ITS_ITT_ALIGN);
 
 	itt = itt_alloc_pool(its->numa_node, sz);
 
-- 
2.34.1

Re: [PATCH v2 1/2] irqchip/gic-v3-its: Share ITS tables with a non-trusted hypervisor

[Catalin Marinas]

On Wed, Oct 02, 2024 at 03:16:29PM +0100, Steven Price wrote:
> Within a realm guest the ITS is emulated by the host. This means the
> allocations must have been made available to the host by a call to
> set_memory_decrypted(). Introduce an allocation function which performs
> this extra call.
> 
> For the ITT use a custom genpool-based allocator that calls
> set_memory_decrypted() for each page allocated, but then suballocates
> the size needed for each ITT. Note that there is no mechanism
> implemented to return pages from the genpool, but it is unlikely the
> peak number of devices will so much larger than the normal level - so
> this isn't expected to be an issue.
> 
> Co-developed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> Tested-by: Will Deacon <will@kernel.org>
> Reviewed-by: Marc Zyngier <maz@kernel.org>
> Signed-off-by: Steven Price <steven.price@arm.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Re: [PATCH v2 2/2] irqchip/gic-v3-its: Rely on genpool alignment

[Catalin Marinas]

On Wed, Oct 02, 2024 at 03:16:30PM +0100, Steven Price wrote:
> its_create_device() over-allocated by ITS_ITT_ALIGN - 1 bytes to ensure
> that an aligned area was available within the allocation. The new
> genpool allocator has its min_alloc_order set to
> get_order(ITS_ITT_ALIGN) so all allocations from it should be
> appropriately aligned.
> 
> Remove the over-allocation from its_create_device() and alignment from
> its_build_mapd_cmd().
> 
> Tested-by: Will Deacon <will@kernel.org>
> Reviewed-by: Marc Zyngier <maz@kernel.org>
> Signed-off-by: Steven Price <steven.price@arm.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Re: [PATCH v2 1/2] irqchip/gic-v3-its: Share ITS tables with a non-trusted hypervisor

[Steven Price]

On 02/10/2024 15:16, Steven Price wrote:
> Within a realm guest the ITS is emulated by the host. This means the
> allocations must have been made available to the host by a call to
> set_memory_decrypted(). Introduce an allocation function which performs
> this extra call.
> 
> For the ITT use a custom genpool-based allocator that calls
> set_memory_decrypted() for each page allocated, but then suballocates
> the size needed for each ITT. Note that there is no mechanism
> implemented to return pages from the genpool, but it is unlikely the
> peak number of devices will so much larger than the normal level - so
> this isn't expected to be an issue.
> 
> Co-developed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> Tested-by: Will Deacon <will@kernel.org>
> Reviewed-by: Marc Zyngier <maz@kernel.org>
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
> Changes since v1:
>  * Drop WARN_ONs and add a comment explaining that, if they fail,
>    set_memory_{en,de}crypted() will already have WARNed and that we are
>    purposefully leaking memory in those cases.
> ---
>  drivers/irqchip/irq-gic-v3-its.c | 151 ++++++++++++++++++++++++++-----
>  1 file changed, 128 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index fdec478ba5e7..7a62fd3a8673 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c

<snip>

> +static void *itt_alloc_pool(int node, int size)
> +{
> +	unsigned long addr;
> +	struct page *page;
> +
> +	if (size >= PAGE_SIZE) {
> +		page = its_alloc_pages_node(node,
> +					    GFP_KERNEL | __GFP_ZERO,
> +					    get_order(size));
> +
> +		if (!page)
> +			return NULL;
> +
> +		return page_address(page);
> +	}
> +
> +	do {
> +		addr = gen_pool_alloc(itt_pool, size);
> +		if (addr)
> +			break;
> +
> +		page = its_alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 1);

Shanker pointed out[1] that this line is wrong. It's allocating 2 pages
not the expect single page because the final argument is the order and
1<<1 is 2.

Can you squash in (or apply as a fix) the following?

Thanks,
Steve

[1] https://lore.kernel.org/r/ed65312a-245c-4fa5-91ad-5d620cab7c6b%40nvidia.com

----8<----
From ada4dc7b3e028a9901219fe0f9212d665a4e610b Mon Sep 17 00:00:00 2001
From: Steven Price <steven.price@arm.com>
Date: Mon, 21 Oct 2024 11:41:05 +0100
Subject: [PATCH] irqchip/gic-v3-its: Fix over allocation in itt_alloc_pool()

itt_alloc_pool() calls its_alloc_pages_node() to allocate an individual
page to add to the pool (for allocations <PAGE_SIZE). However the final
argument of its_alloc_pages_node() is the page order not the number of
pages. Currently it allocates two pages and leaks the second page.
Fix it by passing 0 instead (1 << 0 = 1 page).

Reported-by: Shanker Donthineni <sdonthineni@nvidia.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 drivers/irqchip/irq-gic-v3-its.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 6c1581bf1ae0..526be60e3502 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -261,7 +261,7 @@ static void *itt_alloc_pool(int node, int size)
 		if (addr)
 			break;
 
-		page = its_alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 1);
+		page = its_alloc_pages_node(node, GFP_KERNEL | __GFP_ZERO, 0);
 		if (!page)
 			break;
 
-- 
2.34.1