Re: [PATCH v13 29/30] LoongArch: KVM: Supplement kvm document about LoongArch-specific part

From: zhaotianrui
Date: Thu Jun 15 2023 - 23:52:59 EST


在 2023/6/16 上午10:59, Huacai Chen 写道:
On Fri, Jun 16, 2023 at 10:39 AM zhaotianrui <zhaotianrui@xxxxxxxxxxx> wrote:

在 2023/6/15 下午5:42, Huacai Chen 写道:
Hi, Tianrui,

On Fri, Jun 9, 2023 at 5:09 PM Tianrui Zhao <zhaotianrui@xxxxxxxxxxx> wrote:
Supplement kvm document about LoongArch-specific part, such as add
api introduction for GET/SET_ONE_REG, GET/SET_FPU, GET/SET_MP_STATE,
etc.

Signed-off-by: Tianrui Zhao <zhaotianrui@xxxxxxxxxxx>
---
Documentation/virt/kvm/api.rst | 71 +++++++++++++++++++++++++++++-----
1 file changed, 62 insertions(+), 9 deletions(-)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index add067793b90..ad8e13eab48d 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -416,6 +416,12 @@ Reads the general purpose registers from the vcpu.
__u64 pc;
};

+ /* LoongArch */
+ struct kvm_regs {
Add a " /* out (KVM_GET_REGS) / in (KVM_SET_REGS) */" line as others here?
Thanks, I will add this comment here.

Tianrui Zhao

+ unsigned long gpr[32];
+ unsigned long pc;
+ };
+

4.12 KVM_SET_REGS
-----------------
@@ -506,7 +512,7 @@ translation mode.
------------------

:Capability: basic
-:Architectures: x86, ppc, mips, riscv
+:Architectures: x86, ppc, mips, riscv, loongarch
:Type: vcpu ioctl
:Parameters: struct kvm_interrupt (in)
:Returns: 0 on success, negative on failure.
@@ -592,6 +598,14 @@ b) KVM_INTERRUPT_UNSET

This is an asynchronous vcpu ioctl and can be invoked from any thread.

+LOONGARCH:
+^^^^^^^^^^
+
+Queues an external interrupt to be injected into the virtual CPU. A negative
+interrupt number dequeues the interrupt.
+
+This is an asynchronous vcpu ioctl and can be invoked from any thread.
+

4.17 KVM_DEBUG_GUEST
--------------------
@@ -737,7 +751,7 @@ signal mask.
----------------

:Capability: basic
-:Architectures: x86
+:Architectures: x86, loongarch
:Type: vcpu ioctl
:Parameters: struct kvm_fpu (out)
:Returns: 0 on success, -1 on error
@@ -746,7 +760,7 @@ Reads the floating point state from the vcpu.

::

- /* for KVM_GET_FPU and KVM_SET_FPU */
+ /* x86: for KVM_GET_FPU and KVM_SET_FPU */
struct kvm_fpu {
__u8 fpr[8][16];
__u16 fcw;
@@ -761,12 +775,22 @@ Reads the floating point state from the vcpu.
__u32 pad2;
};

+ /* LoongArch: for KVM_GET_FPU and KVM_SET_FPU */
+ struct kvm_fpu {
+ __u32 fcsr;
+ __u32 none;
Maybe use pad1 as x86 is better.

Huacai
Thanks, this 'none' variable is meaningless, and I will remove it. As
this have already been removed in the actually kvm_fpu structure.
Why remove? I think it is for alignment, just like pad1 for x86.

Huacai

This 'none' variable is not for alignment but a unused register named vcsr in kvm_fpu, so I think it could be removed.

Tianrui Zhao

Tianrui Zhao

+ __u64 fcc;
+ struct kvm_fpureg {
+ __u64 val64[4];
+ }fpr[32];
+ };
+

4.23 KVM_SET_FPU
----------------

:Capability: basic
-:Architectures: x86
+:Architectures: x86, loongarch
:Type: vcpu ioctl
:Parameters: struct kvm_fpu (in)
:Returns: 0 on success, -1 on error
@@ -775,7 +799,7 @@ Writes the floating point state to the vcpu.

::

- /* for KVM_GET_FPU and KVM_SET_FPU */
+ /* x86: for KVM_GET_FPU and KVM_SET_FPU */
struct kvm_fpu {
__u8 fpr[8][16];
__u16 fcw;
@@ -790,6 +814,16 @@ Writes the floating point state to the vcpu.
__u32 pad2;
};

+ /* LoongArch: for KVM_GET_FPU and KVM_SET_FPU */
+ struct kvm_fpu {
+ __u32 fcsr;
+ __u32 none;
I will also remove this 'none' variable.

Tianrui Zhao

+ __u64 fcc;
+ struct kvm_fpureg {
+ __u64 val64[4];
+ }fpr[32];
+ };
+

4.24 KVM_CREATE_IRQCHIP
-----------------------
@@ -1387,7 +1421,7 @@ documentation when it pops into existence).
-------------------

:Capability: KVM_CAP_ENABLE_CAP
-:Architectures: mips, ppc, s390, x86
+:Architectures: mips, ppc, s390, x86, loongarch
:Type: vcpu ioctl
:Parameters: struct kvm_enable_cap (in)
:Returns: 0 on success; -1 on error
@@ -1442,7 +1476,7 @@ for vm-wide capabilities.
---------------------

:Capability: KVM_CAP_MP_STATE
-:Architectures: x86, s390, arm64, riscv
+:Architectures: x86, s390, arm64, riscv, loongarch
:Type: vcpu ioctl
:Parameters: struct kvm_mp_state (out)
:Returns: 0 on success; -1 on error
@@ -1460,7 +1494,7 @@ Possible values are:

========================== ===============================================
KVM_MP_STATE_RUNNABLE the vcpu is currently running
- [x86,arm64,riscv]
+ [x86,arm64,riscv,loongarch]
KVM_MP_STATE_UNINITIALIZED the vcpu is an application processor (AP)
which has not yet received an INIT signal [x86]
KVM_MP_STATE_INIT_RECEIVED the vcpu has received an INIT signal, and is
@@ -1516,11 +1550,14 @@ For riscv:
The only states that are valid are KVM_MP_STATE_STOPPED and
KVM_MP_STATE_RUNNABLE which reflect if the vcpu is paused or not.

+On LoongArch, only the KVM_MP_STATE_RUNNABLE state is used to reflect
+whether the vcpu is runnable.
+
4.39 KVM_SET_MP_STATE
---------------------

:Capability: KVM_CAP_MP_STATE
-:Architectures: x86, s390, arm64, riscv
+:Architectures: x86, s390, arm64, riscv, loongarch
:Type: vcpu ioctl
:Parameters: struct kvm_mp_state (in)
:Returns: 0 on success; -1 on error
@@ -1538,6 +1575,9 @@ For arm64/riscv:
The only states that are valid are KVM_MP_STATE_STOPPED and
KVM_MP_STATE_RUNNABLE which reflect if the vcpu should be paused or not.

+On LoongArch, only the KVM_MP_STATE_RUNNABLE state is used to reflect
+whether the vcpu is runnable.
+
4.40 KVM_SET_IDENTITY_MAP_ADDR
------------------------------

@@ -2839,6 +2879,19 @@ Following are the RISC-V D-extension registers:
0x8020 0000 0600 0020 fcsr Floating point control and status register
======================= ========= =============================================

+LoongArch registers are mapped using the lower 32 bits. The upper 16 bits of
+that is the register group type.
+
+LoongArch csr registers are used to control guest cpu or get status of guest
+cpu, and they have the following id bit patterns::
+
+ 0x9030 0000 0001 00 <reg:5> <sel:3> (64-bit)
+
+LoongArch KVM control registers are used to implement some new defined functions
+such as set vcpu counter or reset vcpu, and they have the following id bit patterns::
+
+ 0x9030 0000 0002 <reg:16>
+

4.69 KVM_GET_ONE_REG
--------------------
--
2.39.1