diff options
| -rw-r--r-- | arch/x86/kvm/mmu/spte.c | 8 | ||||
| -rw-r--r-- | arch/x86/kvm/mmu/spte.h | 14 |
2 files changed, 22 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c index 03ca740bf721..2e08b2a45361 100644 --- a/arch/x86/kvm/mmu/spte.c +++ b/arch/x86/kvm/mmu/spte.c @@ -364,6 +364,14 @@ void kvm_mmu_set_mmio_spte_mask(u64 mmio_value, u64 mmio_mask, u64 access_mask) mmio_value = 0; /* + * The mask must contain only bits that are carved out specifically for + * the MMIO SPTE mask, e.g. to ensure there's no overlap with the MMIO + * generation. + */ + if (WARN_ON(mmio_mask & ~SPTE_MMIO_ALLOWED_MASK)) + mmio_value = 0; + + /* * Disable MMIO caching if the MMIO value collides with the bits that * are used to hold the relocated GFN when the L1TF mitigation is * enabled. This should never fire as there is no known hardware that diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h index 9a9414b8d1d6..f3744eea45f5 100644 --- a/arch/x86/kvm/mmu/spte.h +++ b/arch/x86/kvm/mmu/spte.h @@ -123,6 +123,20 @@ static_assert(!(EPT_SPTE_MMU_WRITABLE & SHADOW_ACC_TRACK_SAVED_MASK)); static_assert(!(SPTE_MMU_PRESENT_MASK & (MMIO_SPTE_GEN_LOW_MASK | MMIO_SPTE_GEN_HIGH_MASK))); +/* + * The SPTE MMIO mask must NOT overlap the MMIO generation bits or the + * MMU-present bit. The generation obviously co-exists with the magic MMIO + * mask/value, and MMIO SPTEs are considered !MMU-present. + * + * The SPTE MMIO mask is allowed to use hardware "present" bits (i.e. all EPT + * RWX bits), all physical address bits (legal PA bits are used for "fast" MMIO + * and so they're off-limits for generation; additional checks ensure the mask + * doesn't overlap legal PA bits), and bit 63 (carved out for future usage). + */ +#define SPTE_MMIO_ALLOWED_MASK (BIT_ULL(63) | GENMASK_ULL(51, 12) | GENMASK_ULL(2, 0)) +static_assert(!(SPTE_MMIO_ALLOWED_MASK & + (SPTE_MMU_PRESENT_MASK | MMIO_SPTE_GEN_LOW_MASK | MMIO_SPTE_GEN_HIGH_MASK))); + #define MMIO_SPTE_GEN_LOW_BITS (MMIO_SPTE_GEN_LOW_END - MMIO_SPTE_GEN_LOW_START + 1) #define MMIO_SPTE_GEN_HIGH_BITS (MMIO_SPTE_GEN_HIGH_END - MMIO_SPTE_GEN_HIGH_START + 1) |