[PATCH v7 21/24] KVM: arm64: vgic-its: Device table save/restore

[Marc Zyngier]

On Sat, May 06 2017 at  4:24:40 pm BST, Eric Auger <eric.auger at redhat.com> wrote:
> This patch saves the device table entries into guest RAM.
> Both flat table and 2 stage tables are supported. DeviceId
> indexing is used.
>
> For each device listed in the device table, we also save
> the translation table using the vgic_its_save/restore_itt
> routines. Those functions will be implemented in a subsequent
> patch.
>
> On restore, devices are re-allocated and their itt are
> re-built.
>
> Signed-off-by: Eric Auger <eric.auger at redhat.com>
>
> ---
> v5 -> v6:
> - accomodate vgic_its_alloc_device change of proto
> - define bit fields for L1 entries
> - s/handle_l1_entry/handle_l1_dte
> - s/ite_esz/dte_esz in handle_l1_dte
> - check BASER valid bit
> - s/nb_eventid_bits/num_eventid_bits
> - new convention for returned values
> - itt functions implemented in subsequent patch
>
> v4 -> v5:
> - sort the device list by deviceid on device table save
> - use defines for shifts and masks
> - use abi->dte_esz
> - clatify entry sizes for L1 and L2 tables
>
> v3 -> v4:
> - use the new proto for its_alloc_device
> - compute_next_devid_offset, vgic_its_flush/restore_itt
>   become static in this patch
> - change in the DTE entry format with the introduction of the
>   valid bit and next field width decrease; ittaddr encoded
>   on its full range
> - fix handle_l1_entry entry handling
> - correct vgic_its_table_restore error handling
>
> v2 -> v3:
> - fix itt_addr bitmask in vgic_its_restore_dte
> - addition of return 0 in vgic_its_restore_ite moved to
>   the ITE related patch
>
> v1 -> v2:
> - use 8 byte format for DTE and ITE
> - support 2 stage format
> - remove kvm parameter
> - ITT flush/restore moved in a separate patch
> - use deviceid indexing
> ---
>  virt/kvm/arm/vgic/vgic-its.c | 194 +++++++++++++++++++++++++++++++++++++++++--
>  virt/kvm/arm/vgic/vgic.h     |  10 +++
>  2 files changed, 199 insertions(+), 5 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index 90afc83..3dea626 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -23,6 +23,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/list.h>
>  #include <linux/uaccess.h>
> +#include <linux/list_sort.h>
>  
>  #include <linux/irqchip/arm-gic-v3.h>
>  
> @@ -1735,7 +1736,8 @@ int vgic_its_attr_regs_access(struct kvm_device *dev,
>  	return ret;
>  }
>  
> -u32 compute_next_devid_offset(struct list_head *h, struct its_device *dev)
> +static u32 compute_next_devid_offset(struct list_head *h,
> +				     struct its_device *dev)
>  {
>  	struct its_device *next;
>  	u32 next_offset;
> @@ -1789,8 +1791,8 @@ typedef int (*entry_fn_t)(struct vgic_its *its, u32 id, void *entry,
>   * Return: < 0 on error, 0 if last element was identified, 1 otherwise
>   * (the last element may not be found on second level tables)
>   */
> -int scan_its_table(struct vgic_its *its, gpa_t base, int size, int esz,
> -		   int start_id, entry_fn_t fn, void *opaque)
> +static int scan_its_table(struct vgic_its *its, gpa_t base, int size, int esz,
> +			  int start_id, entry_fn_t fn, void *opaque)
>  {
>  	void *entry = kzalloc(esz, GFP_KERNEL);
>  	struct kvm *kvm = its->dev->kvm;
> @@ -1825,13 +1827,171 @@ int scan_its_table(struct vgic_its *its, gpa_t base, int size, int esz,
>  	return ret;
>  }
>  
> +static int vgic_its_save_itt(struct vgic_its *its, struct its_device *device)
> +{
> +	return -ENXIO;
> +}
> +
> +static int vgic_its_restore_itt(struct vgic_its *its, struct its_device *dev)
> +{
> +	return -ENXIO;
> +}
> +
> +/**
> + * vgic_its_save_dte - Save a device table entry at a given GPA
> + *
> + * @its: ITS handle
> + * @dev: ITS device
> + * @ptr: GPA
> + */
> +static int vgic_its_save_dte(struct vgic_its *its, struct its_device *dev,
> +			     gpa_t ptr, int dte_esz)
> +{
> +	struct kvm *kvm = its->dev->kvm;
> +	u64 val, itt_addr_field;
> +	u32 next_offset;
> +
> +	itt_addr_field = dev->itt_addr >> 8;
> +	next_offset = compute_next_devid_offset(&its->device_list, dev);
> +	val = (1ULL << KVM_ITS_DTE_VALID_SHIFT |
> +	       ((u64)next_offset << KVM_ITS_DTE_NEXT_SHIFT) |
> +	       (itt_addr_field << KVM_ITS_DTE_ITTADDR_SHIFT) |
> +		(dev->num_eventid_bits - 1));
> +	val = cpu_to_le64(val);
> +	return kvm_write_guest(kvm, ptr, &val, dte_esz);
> +}
> +
> +/**
> + * vgic_its_restore_dte - restore a device table entry
> + *
> + * @its: its handle
> + * @id: device id the DTE corresponds to
> + * @ptr: kernel VA where the 8 byte DTE is located
> + * @opaque: unused
> + *
> + * Return: < 0 on error, 0 if the dte is the last one, id offset to the
> + * next dte otherwise
> + */
> +static int vgic_its_restore_dte(struct vgic_its *its, u32 id,
> +				void *ptr, void *opaque)
> +{
> +	struct its_device *dev;
> +	gpa_t itt_addr;
> +	u8 num_eventid_bits;
> +	u64 entry = *(u64 *)ptr;
> +	bool valid;
> +	u32 offset;
> +	int ret;
> +
> +	entry = le64_to_cpu(entry);
> +
> +	valid = entry >> KVM_ITS_DTE_VALID_SHIFT;
> +	num_eventid_bits = (entry & KVM_ITS_DTE_SIZE_MASK) + 1;
> +	itt_addr = ((entry & KVM_ITS_DTE_ITTADDR_MASK)
> +			>> KVM_ITS_DTE_ITTADDR_SHIFT) << 8;
> +
> +	if (!valid)
> +		return 1;
> +
> +	/* dte entry is valid */
> +	offset = (entry & KVM_ITS_DTE_NEXT_MASK) >> KVM_ITS_DTE_NEXT_SHIFT;
> +
> +	dev = vgic_its_alloc_device(its, id, itt_addr, num_eventid_bits);
> +	if (IS_ERR(dev))
> +		return PTR_ERR(dev);
> +
> +	ret = vgic_its_restore_itt(its, dev);
> +	if (ret)
> +		return ret;

Shouldn't we free the device entry if the restore as failed?

Thanks,

	M.
-- 
Jazz is not dead, it just smell funny.