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Re: [Qemu-devel] [PATCH v3 1/2] intel_iommu: check validity for GAW bits
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v3 1/2] intel_iommu: check validity for GAW bits in CE |
Date: |
Wed, 14 Dec 2016 04:48:42 +0200 |
On Wed, Dec 14, 2016 at 10:09:04AM +0800, Peter Xu wrote:
> Currently vt-d Context Entry (CE) only allows 39/48 bits address width.
> If guest software configured more than that, we complain and report.
>
> Signed-off-by: Peter Xu <address@hidden>
> ---
> hw/i386/intel_iommu.c | 17 ++++++++++++++++-
> hw/i386/intel_iommu_internal.h | 2 ++
> 2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> index 5f3e351..517a2a3 100644
> --- a/hw/i386/intel_iommu.c
> +++ b/hw/i386/intel_iommu.c
> @@ -599,9 +599,19 @@ static inline uint32_t
> vtd_get_level_from_context_entry(VTDContextEntry *ce)
> return 2 + (ce->hi & VTD_CONTEXT_ENTRY_AW);
> }
>
> +/* Return 0 if failed to fetch valid aw */
> static inline uint32_t vtd_get_agaw_from_context_entry(VTDContextEntry *ce)
> {
> - return 30 + (ce->hi & VTD_CONTEXT_ENTRY_AW) * 9;
> + uint8_t aw = (ce->hi & VTD_CONTEXT_ENTRY_AW);
> + /*
> + * According to vt-d spec 10.4.2 bits 12:8, SAGAW only allows
> + * 39/48 bits.
> + */
> + if (aw > VTD_CE_AW_48BIT) {
5-level is almost sure to allow more. I don't see the point of this test.
> + error_report("Context entry address width not supported (aw=%d)" ,
> aw);
> + return 0;
> + }
> + return 30 + aw * 9;
> }
>
> static const uint64_t vtd_paging_entry_rsvd_field[] = {
> @@ -642,6 +652,11 @@ static int vtd_gpa_to_slpte(VTDContextEntry *ce,
> uint64_t gpa, bool is_write,
> uint32_t ce_agaw = vtd_get_agaw_from_context_entry(ce);
> uint64_t access_right_check;
>
> + if (!ce_agaw) {
> + error_report("Illegal context entry AGAW");
> + return -VTD_FR_CONTEXT_ENTRY_INV;
> + }
> +
> /* Check if @gpa is above 2^X-1, where X is the minimum of MGAW in
> CAP_REG
> * and AW in context-entry.
> */
> diff --git a/hw/i386/intel_iommu_internal.h b/hw/i386/intel_iommu_internal.h
> index 11abfa2..e808c67 100644
> --- a/hw/i386/intel_iommu_internal.h
> +++ b/hw/i386/intel_iommu_internal.h
> @@ -406,6 +406,8 @@ typedef struct VTDRootEntry VTDRootEntry;
> #define VTD_CONTEXT_ENTRY_RSVD_LO (0xff0ULL | ~VTD_HAW_MASK)
> /* hi */
> #define VTD_CONTEXT_ENTRY_AW 7ULL /* Adjusted guest-address-width */
> +#define VTD_CE_AW_39BIT 1
> +#define VTD_CE_AW_48BIT 2
> #define VTD_CONTEXT_ENTRY_DID(val) (((val) >> 8) & VTD_DOMAIN_ID_MASK)
> #define VTD_CONTEXT_ENTRY_RSVD_HI 0xffffffffff000080ULL
>
> --
> 2.7.4