[PATCH v6 04/11] arm64: rsi: Add support for checking whether an MMIO is protected
Gavin Shan
gshan at redhat.com
Mon Oct 7 17:24:03 PDT 2024
On 10/5/24 12:42 AM, Steven Price wrote:
> From: Suzuki K Poulose <suzuki.poulose at arm.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.
>
> Reviewed-by: Catalin Marinas <catalin.marinas at arm.com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose at arm.com>
> Signed-off-by: Steven Price <steven.price at arm.com>
> ---
> New patch for v5
> ---
> arch/arm64/include/asm/io.h | 8 ++++++++
> arch/arm64/include/asm/rsi.h | 2 ++
> arch/arm64/include/asm/rsi_cmds.h | 21 +++++++++++++++++++++
> arch/arm64/kernel/rsi.c | 26 ++++++++++++++++++++++++++
> 4 files changed, 57 insertions(+)
>
With the following nitpick addressed:
Reviewed-by: Gavin Shan <gshan at redhat.com>
> diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
> index 1ada23a6ec19..cce445ff8e3f 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_mmio_private(phys_addr_t phys_addr, size_t size)
> +{
> + if (unlikely(is_realm_world()))
> + return arm64_is_protected_mmio(phys_addr, size);
> + return false;
> +}
> +
The function names (arm64_is_{mmio_private, protected_mmio} are indicators to the
MMIO region's state or property. arm64_is_mmio_private() indicates the MMIO region
is 'private MMIO' while arm64_is_protected_mmio() indicates the MMIO region is
'protected MMIO'. They are equivalent and it may be worthy to unify the function
names (indicators) as below.
option#1 option#2
-------- --------
arm64_is_private_mmio arm64_is_protected_mmio
__arm64_is_private_mmio __arm64_is_protected_mmio
> #endif /* __ASM_IO_H */
> diff --git a/arch/arm64/include/asm/rsi.h b/arch/arm64/include/asm/rsi.h
> index acba065eb00e..42ff93c7b0ba 100644
> --- a/arch/arm64/include/asm/rsi.h
> +++ b/arch/arm64/include/asm/rsi.h
> @@ -14,6 +14,8 @@ DECLARE_STATIC_KEY_FALSE(rsi_present);
>
> void __init arm64_rsi_init(void);
>
> +bool arm64_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 b661331c9204..fdb47f690307 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 a6495a64d9bb..d7bba4cee627 100644
> --- a/arch/arm64/kernel/rsi.c
> +++ b/arch/arm64/kernel/rsi.c
> @@ -66,6 +66,32 @@ static void __init arm64_rsi_setup_memory(void)
> }
> }
>
> +bool arm64_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_DEV)
> + break;
> + base = top;
> + }
> +
> + return base >= end;
> +}
> +EXPORT_SYMBOL(arm64_is_protected_mmio);
> +
The function may be worthy to be renamed to __arm64_is_private_mmio, as explained
as above.
> void __init arm64_rsi_init(void)
> {
> if (arm_smccc_1_1_get_conduit() != SMCCC_CONDUIT_SMC)
Thanks,
Gavin
More information about the linux-arm-kernel
mailing list