Re: [PATCH v6 24/29] xen/x86: allow HVM guests to use hypercalls to bring up vCPUs

["Roger Pau Monné" <roger.pau@citrix.com>]

El 30/09/15 a les 12.03, Jan Beulich ha escrit:
>>>> On 29.09.15 at 18:49, <roger.pau@citrix.com> wrote:
>> El 29/09/15 a les 18.20, Jan Beulich ha escrit:
>>>>>> On 29.09.15 at 18:01, <roger.pau@citrix.com> wrote:
>>>> Yes, I should add back all the registers here, so it looks like:
>>>>
>>>>      uint32_t cs_base;
>>>>      uint32_t ds_base;
>>>>      uint32_t ss_base;
>>>>      uint32_t es_base;
>>>>      uint32_t cs_limit;
>>>>      uint32_t ds_limit;
>>>>      uint32_t ss_limit;
>>>>      uint32_t es_limit;
>>>>      uint16_t cs_ar;
>>>>      uint16_t ds_ar;
>>>>      uint16_t ss_ar;
>>>>      uint16_t es_ar;
>>>
>>> Or specify that compat mode entry is via using 32-bit register state.
>>
>> Yes, that should also work. If that's the preference then I guess we 
>> can remove all the selectors stuff from the 64bit structure.
> 
> That's my preference (with the EFER comment then accordingly
> updated). Andrew?

This is what I currently have prototyped according to the comments, it 
should allow starting the vCPU in all possible modes AFAICT.

struct vcpu_hvm_x86_32 {
    uint32_t eax;
    uint32_t ecx;
    uint32_t edx;
    uint32_t ebx;
    uint32_t esp;
    uint32_t ebp;
    uint32_t esi;
    uint32_t edi;
    uint32_t eip;
    uint32_t eflags;

    uint32_t cr0;
    uint32_t cr3;
    uint32_t cr4;

    /*
     * EFER should only be used to set the NXE bit (if required)
     * when starting a vCPU in 32bit mode with paging enabled or
     * to set the LME/LMA bits in order to start the vCPU in
     * compatibility mode.
     */
    uint64_t efer;

    uint32_t cs_base;
    uint32_t ds_base;
    uint32_t ss_base;
    uint32_t es_base;
    uint32_t tr_base;
    uint32_t cs_limit;
    uint32_t ds_limit;
    uint32_t ss_limit;
    uint32_t es_limit;
    uint32_t tr_limit;
    uint16_t cs_ar;
    uint16_t ds_ar;
    uint16_t ss_ar;
    uint16_t es_ar;
    uint16_t tr_ar;
};

struct vcpu_hvm_x86_64 {
    uint64_t rax;
    uint64_t rcx;
    uint64_t rdx;
    uint64_t rbx;
    uint64_t rsp;
    uint64_t rbp;
    uint64_t rsi;
    uint64_t rdi;
    uint64_t rip;
    uint64_t rflags;

    uint64_t cr0;
    uint64_t cr3;
    uint64_t cr4;
    uint64_t efer;

    /*
     * Using VCPU_HVM_MODE_64B implies that the vCPU is launched
     * directly in long mode, so the type of the cached part
     * of the TR register is set to describe a 64-bit TSS (Busy).
     * The cached part of the CS register will also have the L bit
     * set (64-bit code segment).
     *
     * If the user wants to launch the vCPU in compatibility mode
     * the 32-bit structure should be used instead.
     */
};

struct vcpu_hvm_context {
#define VCPU_HVM_MODE_32B 0  /* 32bit fields of the structure will be used. */
#define VCPU_HVM_MODE_64B 1  /* 64bit fields of the structure will be used. */
    uint32_t mode;

    /* CPU registers. */
    union {
        struct vcpu_hvm_x86_32 x86_32;
        struct vcpu_hvm_x86_64 x86_64;
    } cpu_regs;
};

Roger.