build: Fixed build errors and warnings on AArch64

This is a preparing commit to build and test CH on AArch64. All building
issues were fixed, but no functionality was introduced.
For X86, the logic of code was not changed at all.
For ARM, the architecture specific part is still empty. And we applied
some tricks to workaround lint warnings. But such code will be replaced
later by other commits with real functionality.

Signed-off-by: Michael Zhao <michael.zhao@arm.com>

arch/src/aarch64/mod.rs

@@ -3,16 +3,26 @@
 
 pub mod layout;
 
-use memory_model::{GuestAddress, GuestMemory};
+use crate::RegionType;
+use kvm_ioctls::*;
+use vm_memory::{GuestAddress, GuestMemoryMmap, GuestUsize};
 
 /// Stub function that needs to be implemented when aarch64 functionality is added.
-pub fn arch_memory_regions(size: usize) -> Vec<(GuestAddress, usize, RegionType)> {
-    vec![(GuestAddress(0), size, RegionType::Ram)]
+pub fn arch_memory_regions(size: GuestUsize) -> Vec<(GuestAddress, usize, RegionType)> {
+    vec![(GuestAddress(0), size as usize, RegionType::Ram)]
+}
+
+#[derive(Debug, Copy, Clone)]
+/// Specifies the entry point address where the guest must start
+/// executing code.
+pub struct EntryPoint {
+    /// Address in guest memory where the guest must start execution
+    pub entry_addr: GuestAddress,
 }
 
 /// Stub function that needs to be implemented when aarch64 functionality is added.
 pub fn configure_system(
-    _guest_mem: &GuestMemory,
+    _guest_mem: &GuestMemoryMmap,
     _cmdline_addr: GuestAddress,
     _cmdline_size: usize,
     _num_cpus: u8,
@@ -25,3 +35,29 @@ pub fn configure_system(
 pub fn get_reserved_mem_addr() -> usize {
     0
 }
+
+pub fn get_host_cpu_phys_bits() -> u8 {
+    // The value returned here is used to determine the physical address space size
+    // for a VM (IPA size).
+    // In recent kernel versions, the maxium IPA size supported by the host can be
+    // known by querying cap KVM_CAP_ARM_VM_IPA_SIZE. And the IPA size for a
+    // guest can be configured smaller.
+    // But in Cloud-Hypervisor we simply use the maxium value for the VM.
+    // Reference https://lwn.net/Articles/766767/.
+    //
+    // The correct way to query KVM_CAP_ARM_VM_IPA_SIZE is via rust-vmm/kvm-ioctls,
+    // which wraps all IOCTL's and provides easy interface to user hypervisors.
+    // For now the cap hasn't been supported. A separate patch will be submitted to
+    // rust-vmm to add it.
+    // So a hardcoded value is used here as a temporary solution.
+    // It will be replace once rust-vmm/kvm-ioctls is ready.
+    //
+    40
+}
+
+pub fn check_required_kvm_extensions(kvm: &Kvm) -> super::Result<()> {
+    if !kvm.check_extension(Cap::SignalMsi) {
+        return Err(super::Error::CapabilityMissing(Cap::SignalMsi));
+    }
+    Ok(())
+}

arch/src/lib.rs

@@ -22,6 +22,7 @@ extern crate kvm_ioctls;
 extern crate linux_loader;
 extern crate vm_memory;
 
+use kvm_ioctls::*;
 use std::result;
 
 #[derive(Debug)]
@@ -47,6 +48,8 @@ pub enum Error {
     ModlistSetup(vm_memory::GuestMemoryError),
     /// RSDP Beyond Guest Memory
     RSDPPastRamEnd,
+    /// Capability missing
+    CapabilityMissing(Cap),
 }
 pub type Result<T> = result::Result<T, Error>;
 
@@ -73,8 +76,8 @@ pub mod aarch64;
 
 #[cfg(target_arch = "aarch64")]
 pub use aarch64::{
-    arch_memory_regions, configure_system, get_reserved_mem_addr, layout::CMDLINE_MAX_SIZE,
-    layout::CMDLINE_START,
+    arch_memory_regions, check_required_kvm_extensions, configure_system, get_host_cpu_phys_bits,
+    get_reserved_mem_addr, layout::CMDLINE_MAX_SIZE, layout::CMDLINE_START, EntryPoint,
 };
 
 #[cfg(target_arch = "x86_64")]
@@ -82,11 +85,13 @@ pub mod x86_64;
 
 #[cfg(target_arch = "x86_64")]
 pub use x86_64::{
-    arch_memory_regions, configure_system, initramfs_load_addr, layout, layout::CMDLINE_MAX_SIZE,
-    layout::CMDLINE_START, regs, BootProtocol, EntryPoint,
+    arch_memory_regions, check_required_kvm_extensions, configure_system, get_host_cpu_phys_bits,
+    initramfs_load_addr, layout, layout::CMDLINE_MAX_SIZE, layout::CMDLINE_START, regs,
+    BootProtocol, EntryPoint,
 };
 
 /// Safe wrapper for `sysconf(_SC_PAGESIZE)`.
+#[cfg(target_arch = "x86_64")]
 #[inline(always)]
 fn pagesize() -> usize {
     // Trivially safe

arch/src/x86_64/mod.rs

@@ -13,9 +13,9 @@ pub mod layout;
 #[cfg(not(feature = "acpi"))]
 mod mptable;
 pub mod regs;
-
 use crate::InitramfsConfig;
 use crate::RegionType;
+use kvm_ioctls::*;
 use linux_loader::loader::bootparam::{boot_params, setup_header};
 use linux_loader::loader::elf::start_info::{
     hvm_memmap_table_entry, hvm_modlist_entry, hvm_start_info,
@@ -459,6 +459,47 @@ pub fn initramfs_load_addr(
     Ok(aligned_addr)
 }
 
+pub fn get_host_cpu_phys_bits() -> u8 {
+    use std::arch::x86_64;
+    unsafe {
+        let leaf = x86_64::__cpuid(0x8000_0000);
+
+        // Detect and handle AMD SME (Secure Memory Encryption) properly.
+        // Some physical address bits may become reserved when the feature is enabled.
+        // See AMD64 Architecture Programmer's Manual Volume 2, Section 7.10.1
+        let reduced = if leaf.eax >= 0x8000_001f
+            && leaf.ebx == 0x6874_7541    // Vendor ID: AuthenticAMD
+            && leaf.ecx == 0x444d_4163
+            && leaf.edx == 0x6974_6e65
+            && x86_64::__cpuid(0x8000_001f).eax & 0x1 != 0
+        {
+            (x86_64::__cpuid(0x8000_001f).ebx >> 6) & 0x3f
+        } else {
+            0
+        };
+
+        if leaf.eax >= 0x8000_0008 {
+            let leaf = x86_64::__cpuid(0x8000_0008);
+            ((leaf.eax & 0xff) - reduced) as u8
+        } else {
+            36
+        }
+    }
+}
+
+pub fn check_required_kvm_extensions(kvm: &Kvm) -> super::Result<()> {
+    if !kvm.check_extension(Cap::SignalMsi) {
+        return Err(super::Error::CapabilityMissing(Cap::SignalMsi));
+    }
+    if !kvm.check_extension(Cap::TscDeadlineTimer) {
+        return Err(super::Error::CapabilityMissing(Cap::TscDeadlineTimer));
+    }
+    if !kvm.check_extension(Cap::SplitIrqchip) {
+        return Err(super::Error::CapabilityMissing(Cap::SplitIrqchip));
+    }
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;