Enum MemCacheType

pub enum MemCacheType {
    CacheCoherent,
    CacheNonCoherent,
}

Signal to the hypervisor on kernels that support the KVM_CAP_USER_CONFIGURE_NONCOHERENT_DMA (or equivalent) that during user memory region (memslot) configuration, a guest page’s memtype should be considered in SLAT effective memtype determination rather than implicitly respecting only the host page’s memtype.

This explicit control is needed for Virtio devices (e.g. gpu) that configure memslots for host WB page mappings with guest WC page mappings. See b/316337317, b/360295883 for more detail.

Variants

CacheCoherent

Don’t provide any explicit instruction to the hypervisor on how it should determine a memslot’s effective memtype.

On KVM-VMX (Intel), this means that the memslot is flagged with VMX_EPT_IPAT_BIT such that only the host memtype is respected.

CacheNonCoherent

explicitly instruct the hypervisor to respect the guest page’s memtype when determining the memslot’s effective memtype.

On KVM-VMX (Intel), this means the memslot is NOT flagged with VMX_EPT_IPAT_BIT, and the effective memtype will generally decay to the weaker amongst the host/guest memtypes and the MTRR for the physical address.

Trait Implementations

impl Clone for MemCacheType

fn clone(&self) -> MemCacheType

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for MemCacheType

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for MemCacheType

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for MemCacheType

fn eq(&self, other: &MemCacheType) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for MemCacheType

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Copy for MemCacheType

impl Eq for MemCacheType

impl StructuralPartialEq for MemCacheType