On 25/01/19 16:40, Sean Christopherson wrote: > KVM's assembly for transitioning to/from a VMX guest is currently > implemented via inline asm. At best it can be called "inscrutable", at > worst, well, that can't be printed here. > > This series' ultimate goal is to move the transition code to a proper > assembly sub-routine that can be directly invoked from C code. > Unsurprisingly, making that happen requires a large number of patches > to carefully disarm all of the booby traps hiding in the shadows. > > This series does NOT apply directly on the official KVM branches, but > rather on the official branches plus the patch that splits out a small > amount of vmx_vcpu_run() code to a helper, __vmx_vcpu_run()[1]. Adding > the helper function fixes a bug for kernel v5.0, i.e. absolutely should > be applied before this series, and not accounting for that change would > result in non-trivial conflicts. > > A few patches in this series are carried over from the back half of the > series that moved VM-Enter and VM-Exit to proper assembly[2], but is > versioned as a different series given the much more ambitious end goal. > > v1: https://patchwork.kernel.org/cover/10771525/ > > v2: https://patchwork.kernel.org/cover/10779721/ > - Fully tested 32-bit, amazingly there was no breakage. > - Use 'b' and '=b' for asm constraints instead of trying to get fancy > with 'bl' and '=ebx'. [Paolo] > - Rename explicit VCPU reg indicides to __VCPU_REGS_R*. [Paolo] > - Add Jim and Konrad's Reviewed-by tags. > > v3: > - Add patch to zero out registers that are reloaded from the stack. [Paolo] > - Let compiler choose reg for @vm_fail in nested early checks. [Jim] > - Add more "Reviewed-by Jim" tags. > - Split "Make the vCPU-run asm routine callable from C" into separate > patches to make each incremental change bisect-friendly. > > [1] https://patchwork.kernel.org/patch/10765309/ > [2] https://patchwork.kernel.org/cover/10739549/ > > Sean Christopherson (33): > KVM: VMX: Compare only a single byte for VMCS' "launched" in vCPU-run > KVM: nVMX: Check a single byte for VMCS "launched" in nested early > checks > KVM: VMX: Zero out *all* general purpose registers after VM-Exit > KVM: VMX: Modify only RSP when creating a placeholder for guest's RCX > KVM: VMX: Save RSI to an unused output in the vCPU-run asm blob > KVM: VMX: Manually load RDX in vCPU-run asm blob > KVM: VMX: Let the compiler save/load RDX during vCPU-run > KVM: nVMX: Remove a rogue "rax" clobber from > nested_vmx_check_vmentry_hw() > KVM: nVMX: Drop STACK_FRAME_NON_STANDARD from > nested_vmx_check_vmentry_hw() > KVM: nVMX: Explicitly reference the scratch reg in nested early checks > KVM: nVMX: Capture VM-Fail to a local var in > nested_vmx_check_vmentry_hw() > KVM: nVMX: Capture VM-Fail via CC_{SET,OUT} in nested early checks > KVM: nVMX: Reference vmx->loaded_vmcs->launched directly > KVM: nVMX: Let the compiler select the reg for holding HOST_RSP > KVM: nVMX: Cache host_rsp on a per-VMCS basis > KVM: VMX: Load/save guest CR2 via C code in __vmx_vcpu_run() > KVM: VMX: Update VMCS.HOST_RSP via helper C function > KVM: VMX: Pass "launched" directly to the vCPU-run asm blob > KVM: VMX: Invert the ordering of saving guest/host scratch reg at > VM-Enter > KVM: VMX: Don't save guest registers after VM-Fail > KVM: VMX: Use vcpu->arch.regs directly when saving/loading guest state > KVM: x86: Explicitly #define the VCPU_REGS_* indices > KVM: VMX: Use #defines in place of immediates in VM-Enter inline asm > KVM: VMX: Create a stack frame in vCPU-run > KVM: VMX: Move vCPU-run code to a proper assembly routine > KVM: VMX: Fold __vmx_vcpu_run() back into vmx_vcpu_run() > KVM: VMX: Rename ____vmx_vcpu_run() to __vmx_vcpu_run() > KVM: VMX: Use RAX as the scratch register during vCPU-run > KVM: VMX: Pass @launched to the vCPU-run asm via standard ABI regs > KVM: VMX: Return VM-Fail from vCPU-run assembly via standard ABI reg > KVM: VMX: Preserve callee-save registers in vCPU-run asm sub-routine > KVM: VMX: Call vCPU-run asm sub-routine from C and remove clobbering > KVM: VMX: Reorder clearing of registers in the vCPU-run assembly flow > > arch/x86/include/asm/kvm_host.h | 33 +++--- > arch/x86/include/asm/kvm_vcpu_regs.h | 25 ++++ > arch/x86/kvm/vmx/nested.c | 53 ++++----- > arch/x86/kvm/vmx/vmcs.h | 1 + > arch/x86/kvm/vmx/vmenter.S | 170 +++++++++++++++++++++++++++ > arch/x86/kvm/vmx/vmx.c | 160 +++---------------------- > arch/x86/kvm/vmx/vmx.h | 3 +- > 7 files changed, 252 insertions(+), 193 deletions(-) > create mode 100644 arch/x86/include/asm/kvm_vcpu_regs.h > Queued, thanks. Paolo
