Re: [Xen-devel] [PATCH V3 29/29] x86/vvtd: save and restore emulated VT-d

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, Sep 21, 2017 at 11:02:10PM -0400, Lan Tianyu wrote:
> From: Chao Gao <chao.gao@xxxxxxxxx>
> 
> Provide a save-restore pair to save/restore registers and non-register
> status.
> 
> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
> Signed-off-by: Lan Tianyu <tianyu.lan@xxxxxxxxx>
> ---
> v3:
>  - use one entry to save both vvtd registers and other intermediate
>  state
> ---
>  xen/drivers/passthrough/vtd/vvtd.c     | 66 
> ++++++++++++++++++++++++++--------
>  xen/include/public/arch-x86/hvm/save.h | 25 ++++++++++++-
>  2 files changed, 76 insertions(+), 15 deletions(-)
> 
> diff --git a/xen/drivers/passthrough/vtd/vvtd.c 
> b/xen/drivers/passthrough/vtd/vvtd.c
> index 668d0c9..2aecd93 100644
> --- a/xen/drivers/passthrough/vtd/vvtd.c
> +++ b/xen/drivers/passthrough/vtd/vvtd.c
> @@ -28,11 +28,13 @@
>  #include <asm/current.h>
>  #include <asm/event.h>
>  #include <asm/hvm/domain.h>
> +#include <asm/hvm/save.h>
>  #include <asm/hvm/support.h>
>  #include <asm/io_apic.h>
>  #include <asm/page.h>
>  #include <asm/p2m.h>
>  #include <asm/viommu.h>
> +#include <public/hvm/save.h>
>  
>  #include "iommu.h"
>  #include "vtd.h"
> @@ -40,20 +42,6 @@
>  /* Supported capabilities by vvtd */
>  unsigned int vvtd_caps = VIOMMU_CAP_IRQ_REMAPPING;
>  
> -struct hvm_hw_vvtd_status {
> -    uint32_t eim_enabled : 1,
> -             intremap_enabled : 1;
> -    uint32_t fault_index;
> -    uint32_t irt_max_entry;
> -    /* Interrupt remapping table base gfn */
> -    uint64_t irt;
> -};
> -
> -union hvm_hw_vvtd_regs {
> -    uint32_t data32[256];
> -    uint64_t data64[128];
> -};
> -
>  struct vvtd {
>      /* Address range of remapping hardware register-set */
>      uint64_t base_addr;
> @@ -1057,6 +1045,56 @@ static bool vvtd_is_remapping(struct domain *d,
>      return 0;
>  }
>  
> +static int vvtd_load(struct domain *d, hvm_domain_context_t *h)
> +{
> +    struct hvm_hw_vvtd *hw_vvtd;
> +
> +    if ( !domain_vvtd(d) )
> +        return -ENODEV;
> +
> +    hw_vvtd = xmalloc(struct hvm_hw_vvtd);
> +    if ( !hw_vvtd )
> +        return -ENOMEM;
> +
> +    if ( hvm_load_entry(VVTD, h, hw_vvtd) )
> +    {
> +        xfree(hw_vvtd);
> +        return -EINVAL;
> +    }

If you declare hvm_hw_vvtd_regs as a field inside of
hvm_hw_vvtd_status you won't need to do this alloc + memcpy, bnecause
you could directly load it to domain_vvtd.

In any case, I think the code here is going to change due to all the
other comments on the previous patches.

Thanks, Roger.

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