xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

KVM: x86: Omit caching logic for always-available GPRs

Browse Source 
Except for RSP and RIP, which are held in VMX's VMCS, GPRs are always
treated "available and dirtly" on both VMX and SVM, i.e. are
unconditionally loaded/saved immediately before/after VM-Enter/VM-Exit.

Eliminating the unnecessary caching code reduces the size of KVM by a
non-trivial amount, much of which comes from the most common code paths.
E.g. on x86_64, kvm_emulate_cpuid() is reduced from 342 to 182 bytes and
kvm_emulate_hypercall() from 1362 to 1143, with the total size of KVM
dropping by ~1000 bytes.  With CONFIG_RETPOLINE=y, the numbers are even
more pronounced, e.g.: 353->182, 1418->1172 and well over 2000 bytes.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson
2019-04-30 10:36:17 -07:00
committed by Paolo Bonzini
parent 0c55671f84
commit de3cd117ed
6 changed files with 105 additions and 80 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
arch/x86/kvm/hyperv.c
View File

@@ -1526,10 +1526,10 @@ static void kvm_hv_hypercall_set_result(struct kvm_vcpu *vcpu, u64 result)
longmode = is_64_bit_mode(vcpu);
if (longmode)
kvm_register_write(vcpu, VCPU_REGS_RAX, result);
kvm_rax_write(vcpu, result);
else {
kvm_register_write(vcpu, VCPU_REGS_RDX, result >> 32);
kvm_register_write(vcpu, VCPU_REGS_RAX, result & 0xffffffff);
kvm_rdx_write(vcpu, result >> 32);
kvm_rax_write(vcpu, result & 0xffffffff);
}
}
@@ -1602,18 +1602,18 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
longmode = is_64_bit_mode(vcpu);
if (!longmode) {
param = ((u64)kvm_register_read(vcpu, VCPU_REGS_RDX) << 32) |
(kvm_register_read(vcpu, VCPU_REGS_RAX) & 0xffffffff);
ingpa = ((u64)kvm_register_read(vcpu, VCPU_REGS_RBX) << 32) |
(kvm_register_read(vcpu, VCPU_REGS_RCX) & 0xffffffff);
outgpa = ((u64)kvm_register_read(vcpu, VCPU_REGS_RDI) << 32) |
(kvm_register_read(vcpu, VCPU_REGS_RSI) & 0xffffffff);
param = ((u64)kvm_rdx_read(vcpu) << 32) |
(kvm_rax_read(vcpu) & 0xffffffff);
ingpa = ((u64)kvm_rbx_read(vcpu) << 32) |
(kvm_rcx_read(vcpu) & 0xffffffff);
outgpa = ((u64)kvm_rdi_read(vcpu) << 32) |
(kvm_rsi_read(vcpu) & 0xffffffff);
}
#ifdef CONFIG_X86_64
else {
param = kvm_register_read(vcpu, VCPU_REGS_RCX);
ingpa = kvm_register_read(vcpu, VCPU_REGS_RDX);
outgpa = kvm_register_read(vcpu, VCPU_REGS_R8);
param = kvm_rcx_read(vcpu);
ingpa = kvm_rdx_read(vcpu);
outgpa = kvm_r8_read(vcpu);
}
#endif