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Message-ID: <9df7db0e-649f-4d19-b1bc-c1919d3d8c4c@redhat.com>
Date: Fri, 6 Sep 2024 14:52:12 +1000
From: Gavin Shan <gshan@...hat.com>
To: Steven Price <steven.price@....com>, kvm@...r.kernel.org,
kvmarm@...ts.linux.dev
Cc: Catalin Marinas <catalin.marinas@....com>, Marc Zyngier <maz@...nel.org>,
Will Deacon <will@...nel.org>, James Morse <james.morse@....com>,
Oliver Upton <oliver.upton@...ux.dev>,
Suzuki K Poulose <suzuki.poulose@....com>, Zenghui Yu
<yuzenghui@...wei.com>, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, Joey Gouly <joey.gouly@....com>,
Alexandru Elisei <alexandru.elisei@....com>,
Christoffer Dall <christoffer.dall@....com>, Fuad Tabba <tabba@...gle.com>,
linux-coco@...ts.linux.dev,
Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
Shanker Donthineni <sdonthineni@...dia.com>, Alper Gun <alpergun@...gle.com>
Subject: Re: [PATCH v5 07/19] arm64: rsi: Add support for checking whether an
MMIO is protected
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@....com>
>>
>> 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@....com>
>> Signed-off-by: Steven Price <steven.price@....com>
>> ---
>> 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
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