Re: [PATCH v13 10/48] arm64: RMI: Ensure that the RMM has GPT entries for memory

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 18/03/2026 15:53, Steven Price wrote:
> The RMM may not be tracking all the memory of the system at boot. Create
> the necessary tracking state and GPTs within the RMM so that all boot
> memory can be delegated to the RMM as needed during runtime.
> 
> Note: support is currently missing for SROs which means that if the RMM
> needs memory donating this will fail (and render CCA unusable in Linux).
> 
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
> New patch for v13
> ---
>   arch/arm64/kvm/rmi.c | 89 ++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 89 insertions(+)
> 
> diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c
> index 9590dff9a2c1..80aedc85e94a 100644
> --- a/arch/arm64/kvm/rmi.c
> +++ b/arch/arm64/kvm/rmi.c
> @@ -4,6 +4,7 @@
>    */
>   
>   #include <linux/kvm_host.h>
> +#include <linux/memblock.h>
>   
>   #include <asm/kvm_pgtable.h>
>   #include <asm/rmi_cmds.h>
> @@ -56,6 +57,18 @@ static int rmi_check_version(void)
>   	return 0;
>   }
>   
> +/*
> + * These are the 'default' sizes when passing 0 as the tracking_region_size.

This is a little bit vague. Should we explicitly mention :

"For now we set the tracking_region_size to 0 for RMI_RMM_CONFIG_SET()"


> + * TODO: Support other granule sizes

nit: s/granule/Tracking/

Suzuki


> + */
> +#ifdef CONFIG_PAGE_SIZE_4KB
> +#define RMM_GRANULE_TRACKING_SIZE	SZ_1G
> +#elif defined(CONFIG_PAGE_SIZE_16KB)
> +#define RMM_GRANULE_TRACKING_SIZE	SZ_32M
> +#elif defined(CONFIG_PAGE_SIZE_64KB)
> +#define RMM_GRANULE_TRACKING_SIZE	SZ_512M
> +#endif
> +
>   static int rmi_configure(void)
>   {
>   	struct rmm_config *config __free(free_page) = NULL;
> @@ -95,6 +108,80 @@ static int rmi_configure(void)
>   	return 0;
>   }
>   
> +static int rmi_verify_memory_tracking(phys_addr_t start, phys_addr_t end)
> +{
> +	start = ALIGN_DOWN(start, RMM_GRANULE_TRACKING_SIZE);
> +	end = ALIGN(end, RMM_GRANULE_TRACKING_SIZE);
> +
> +	while (start < end) {
> +		unsigned long ret, category, state;
> +
> +		ret = rmi_granule_tracking_get(start, &category, &state);
> +		if (ret != RMI_SUCCESS ||
> +		    state != RMI_TRACKING_FINE ||
> +		    category != RMI_MEM_CATEGORY_CONVENTIONAL) {
> +			/* TODO: Set granule tracking in this case */
> +			kvm_err("Granule tracking for region isn't fine/conventional: %llx",
> +				start);
> +			return -ENODEV;
> +		}
> +		start += RMM_GRANULE_TRACKING_SIZE;
> +	}
> +
> +	return 0;
> +}
> +
> +static unsigned long rmi_l0gpt_size(void)
> +{
> +	return 1UL << (30 + FIELD_GET(RMI_FEATURE_REGISTER_1_L0GPTSZ,
> +				      rmm_feat_reg1));
> +}
> +
> +static int rmi_create_gpts(phys_addr_t start, phys_addr_t end)
> +{
> +	unsigned long l0gpt_sz = rmi_l0gpt_size();
> +
> +	start = ALIGN_DOWN(start, l0gpt_sz);
> +	end = ALIGN(end, l0gpt_sz);
> +
> +	while (start < end) {
> +		int ret = rmi_gpt_l1_create(start);
> +
> +		if (ret && ret != RMI_ERROR_GPT) {
> +			/*
> +			 * FIXME: Handle SRO so that memory can be donated for
> +			 * the tables.
> +			 */
> +			kvm_err("GPT Level1 table missing for %llx\n", start);
> +			return -ENOMEM;
> +		}
> +		start += l0gpt_sz;
> +	}
> +
> +	return 0;
> +}
> +
> +static int rmi_init_metadata(void)
> +{
> +	phys_addr_t start, end;
> +	const struct memblock_region *r;
> +
> +	for_each_mem_region(r) {
> +		int ret;
> +
> +		start = memblock_region_memory_base_pfn(r) << PAGE_SHIFT;
> +		end = memblock_region_memory_end_pfn(r) << PAGE_SHIFT;
> +		ret = rmi_verify_memory_tracking(start, end);
> +		if (ret)
> +			return ret;
> +		ret = rmi_create_gpts(start, end);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
>   static int rmm_check_features(void)
>   {
>   	if (kvm_lpa2_is_enabled() && !rmi_has_feature(RMI_FEATURE_REGISTER_0_LPA2)) {
> @@ -120,6 +207,8 @@ void kvm_init_rmi(void)
>   		return;
>   	if (rmi_configure())
>   		return;
> +	if (rmi_init_metadata())
> +		return;
>   
>   	/* Future patch will enable static branch kvm_rmi_is_available */
>   }