Re: [PATCH v5 07/19] arm64: rsi: Add support for checking whether an MMIO is protected
From: Gavin Shan
Date: Fri Sep 06 2024 - 00:53:19 EST
On 9/6/24 2:32 PM, Gavin Shan wrote:
On 8/19/24 11:19 PM, Steven Price wrote:
From: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
On Arm CCA, with RMM-v1.0, all MMIO regions are shared. However, in
the future, an Arm CCA-v1.0 compliant guest may be run in a lesser
privileged partition in the Realm World (with Arm CCA-v1.1 Planes
feature). In this case, some of the MMIO regions may be emulated
by a higher privileged component in the Realm world, i.e, protected.
Thus the guest must decide today, whether a given MMIO region is shared
vs Protected and create the stage1 mapping accordingly. On Arm CCA, this
detection is based on the "IPA State" (RIPAS == RIPAS_IO). Provide a
helper to run this check on a given range of MMIO.
Also, provide a arm64 helper which may be hooked in by other solutions.
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Steven Price <steven.price@xxxxxxx>
---
New patch for v5
---
arch/arm64/include/asm/io.h | 8 ++++++++
arch/arm64/include/asm/rsi.h | 3 +++
arch/arm64/include/asm/rsi_cmds.h | 21 +++++++++++++++++++++
arch/arm64/kernel/rsi.c | 26 ++++++++++++++++++++++++++
4 files changed, 58 insertions(+)
diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
index 1ada23a6ec19..a6c551c5e44e 100644
--- a/arch/arm64/include/asm/io.h
+++ b/arch/arm64/include/asm/io.h
@@ -17,6 +17,7 @@
#include <asm/early_ioremap.h>
#include <asm/alternative.h>
#include <asm/cpufeature.h>
+#include <asm/rsi.h>
/*
* Generic IO read/write. These perform native-endian accesses.
@@ -318,4 +319,11 @@ extern bool arch_memremap_can_ram_remap(resource_size_t offset, size_t size,
unsigned long flags);
#define arch_memremap_can_ram_remap arch_memremap_can_ram_remap
+static inline bool arm64_is_iomem_private(phys_addr_t phys_addr, size_t size)
+{
+ if (unlikely(is_realm_world()))
+ return arm64_rsi_is_protected_mmio(phys_addr, size);
+ return false;
+}
+
#endif /* __ASM_IO_H */
diff --git a/arch/arm64/include/asm/rsi.h b/arch/arm64/include/asm/rsi.h
index 2bc013badbc3..e31231b50b6a 100644
--- a/arch/arm64/include/asm/rsi.h
+++ b/arch/arm64/include/asm/rsi.h
@@ -13,6 +13,9 @@ DECLARE_STATIC_KEY_FALSE(rsi_present);
void __init arm64_rsi_init(void);
void __init arm64_rsi_setup_memory(void);
+
+bool arm64_rsi_is_protected_mmio(phys_addr_t base, size_t size);
+
static inline bool is_realm_world(void)
{
return static_branch_unlikely(&rsi_present);
diff --git a/arch/arm64/include/asm/rsi_cmds.h b/arch/arm64/include/asm/rsi_cmds.h
index 968b03f4e703..c2363f36d167 100644
--- a/arch/arm64/include/asm/rsi_cmds.h
+++ b/arch/arm64/include/asm/rsi_cmds.h
@@ -45,6 +45,27 @@ static inline unsigned long rsi_get_realm_config(struct realm_config *cfg)
return res.a0;
}
+static inline unsigned long rsi_ipa_state_get(phys_addr_t start,
+ phys_addr_t end,
+ enum ripas *state,
+ phys_addr_t *top)
+{
+ struct arm_smccc_res res;
+
+ arm_smccc_smc(SMC_RSI_IPA_STATE_GET,
+ start, end, 0, 0, 0, 0, 0,
+ &res);
+
+ if (res.a0 == RSI_SUCCESS) {
+ if (top)
+ *top = res.a1;
+ if (state)
+ *state = res.a2;
+ }
+
+ return res.a0;
+}
+
static inline unsigned long rsi_set_addr_range_state(phys_addr_t start,
phys_addr_t end,
enum ripas state,
diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index e968a5c9929e..381a5b9a5333 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c
@@ -67,6 +67,32 @@ void __init arm64_rsi_setup_memory(void)
}
}
+bool arm64_rsi_is_protected_mmio(phys_addr_t base, size_t size)
+{
+ enum ripas ripas;
+ phys_addr_t end, top;
+
+ /* Overflow ? */
+ if (WARN_ON(base + size < base))
+ return false;
+
+ end = ALIGN(base + size, RSI_GRANULE_SIZE);
+ base = ALIGN_DOWN(base, RSI_GRANULE_SIZE);
+
+ while (base < end) {
+ if (WARN_ON(rsi_ipa_state_get(base, end, &ripas, &top)))
+ break;
+ if (WARN_ON(top <= base))
+ break;
+ if (ripas != RSI_RIPAS_IO)
+ break;
+ base = top;
+ }
+
+ return (size && base >= end);
+}
The unexpected calltrace is continuously observed with host/v4, guest/v5 and
latest upstream tf-rmm on 'WARN_ON(top <= base)' because @top is never updated
by the latest tf-rmm. The following call path indicates how SMC_RSI_IPA_STATE_GET
is handled by tf-rmm. I don't see RSI_RIPAS_IO is defined there and @top is
updated.
[ 0.000000] ------------[ cut here ]------------
[ 0.000000] WARNING: CPU: 0 PID: 0 at arch/arm64/kernel/rsi.c:103 arm64_rsi_is_protected_mmio+0xf0/0x110
[ 0.000000] Modules linked in:
[ 0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 6.11.0-rc1-gavin-g3527d001084e #1
[ 0.000000] Hardware name: linux,dummy-virt (DT)
[ 0.000000] pstate: 200000c5 (nzCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 0.000000] pc : arm64_rsi_is_protected_mmio+0xf0/0x110
[ 0.000000] lr : arm64_rsi_is_protected_mmio+0x80/0x110
[ 0.000000] sp : ffffcd7097053bf0
[ 0.000000] x29: ffffcd7097053c30 x28: 0000000000000000 x27: 0000000000000000
[ 0.000000] x26: 00000000000003d0 x25: 00000000ffffff8e x24: ffffcd7096831bd0
[ 0.000000] x23: ffffcd7097053c08 x22: 00000000c4000198 x21: 0000000000001000
[ 0.000000] x20: 0000000001001000 x19: 0000000001000000 x18: 0000000000000002
[ 0.000000] x17: 0000000000000000 x16: 0000000000000010 x15: 0001000080000000
[ 0.000000] x14: 0068000000000703 x13: ffffffffff5fe000 x12: ffffcd7097053ba4
[ 0.000000] x11: 00000000000003d0 x10: ffffcd7097053bc4 x9 : 0000000000000444
[ 0.000000] x8 : ffffffffff5fe000 x7 : 0000000000000000 x6 : 0000000000000000
[ 0.000000] x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000
[ 0.000000] x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
[ 0.000000] Call trace:
[ 0.000000] arm64_rsi_is_protected_mmio+0xf0/0x110
[ 0.000000] set_fixmap_io+0x8c/0xd0
[ 0.000000] of_setup_earlycon+0xa0/0x294
[ 0.000000] early_init_dt_scan_chosen_stdout+0x104/0x1dc
[ 0.000000] acpi_boot_table_init+0x1a4/0x2d8
[ 0.000000] setup_arch+0x240/0x610
[ 0.000000] start_kernel+0x6c/0x708
[ 0.000000] __primary_switched+0x80/0x88
I have local changes like below to avoid the unexpected calltrace.
diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
index 9cb3353e5cbf..3d132d45fd83 100644
--- a/arch/arm64/kernel/rsi.c
+++ b/arch/arm64/kernel/rsi.c
@@ -100,14 +100,15 @@ bool arm64_rsi_is_protected_mmio(phys_addr_t base, size_t size)
while (base < end) {
if (WARN_ON(rsi_ipa_state_get(base, end, &ripas, &top)))
break;
- if (WARN_ON(top <= base))
+ if (WARN_ON(top && top <= base))
break;
if (ripas != RSI_RIPAS_IO)
break;
- base = top;
+
+ base = top ? top : end;
}
- return (size && base >= end);
+ return base >= end;
Thanks,
Gavin