Re: [RFC v19 13/15] i386: slit svm_helper into softmmu and stub-only user

[Claudio Fontana <cfontana@suse.de>]

On 2/16/21 11:46 AM, Claudio Fontana wrote:
> XXX Should we assert that cpu hidden flag SVME is not set,
> when attempting to generate VMRUN and related instructions
> in CONFIG_USER_ONLY?
> 
> XXX Similarily, should we check for CONFIG_USER_ONLY when
> attempting to cpu_load_efer?
> 
> Signed-off-by: Claudio Fontana <cfontana@suse.de>
> Cc: Paolo Bonzini <pbonzini@redhat.com>


Highlighting these two questions above to Paolo,

I noticed also a call to cpu_load_efer() in gdbstub.c,

        case IDX_CTL_EFER_REG:
            if (env->hflags & HF_CS64_MASK) {
                cpu_load_efer(env, ldq_p(mem_buf));
                return 8;
            }
            cpu_load_efer(env, ldl_p(mem_buf));
            return 4;

        }

Should this somehow restricted for user-mode, as it has the potential to set HF_SVME ?


> ---
>  target/i386/tcg/{ => softmmu}/svm_helper.c | 62 +-----------------
>  target/i386/tcg/user/svm_stubs.c           | 76 ++++++++++++++++++++++
>  target/i386/tcg/meson.build                |  1 -
>  target/i386/tcg/softmmu/meson.build        |  1 +
>  target/i386/tcg/user/meson.build           |  1 +
>  5 files changed, 80 insertions(+), 61 deletions(-)
>  rename target/i386/tcg/{ => softmmu}/svm_helper.c (96%)
>  create mode 100644 target/i386/tcg/user/svm_stubs.c
> 
> diff --git a/target/i386/tcg/svm_helper.c b/target/i386/tcg/softmmu/svm_helper.c
> similarity index 96%
> rename from target/i386/tcg/svm_helper.c
> rename to target/i386/tcg/softmmu/svm_helper.c
> index 097bb9b83d..a2c9819330 100644
> --- a/target/i386/tcg/svm_helper.c
> +++ b/target/i386/tcg/softmmu/svm_helper.c
> @@ -1,5 +1,5 @@
>  /*
> - *  x86 SVM helpers
> + *  x86 SVM helpers (softmmu-only)
>   *
>   *  Copyright (c) 2003 Fabrice Bellard
>   *
> @@ -22,66 +22,10 @@
>  #include "exec/helper-proto.h"
>  #include "exec/exec-all.h"
>  #include "exec/cpu_ldst.h"
> -#include "helper-tcg.h"
> +#include "tcg/helper-tcg.h"
>  
>  /* Secure Virtual Machine helpers */
>  
> -#if defined(CONFIG_USER_ONLY)
> -
> -void helper_vmrun(CPUX86State *env, int aflag, int next_eip_addend)
> -{
> -}
> -
> -void helper_vmmcall(CPUX86State *env)
> -{
> -}
> -
> -void helper_vmload(CPUX86State *env, int aflag)
> -{
> -}
> -
> -void helper_vmsave(CPUX86State *env, int aflag)
> -{
> -}
> -
> -void helper_stgi(CPUX86State *env)
> -{
> -}
> -
> -void helper_clgi(CPUX86State *env)
> -{
> -}
> -
> -void helper_skinit(CPUX86State *env)
> -{
> -}
> -
> -void helper_invlpga(CPUX86State *env, int aflag)
> -{
> -}
> -
> -void cpu_vmexit(CPUX86State *nenv, uint32_t exit_code, uint64_t exit_info_1,
> -                uintptr_t retaddr)
> -{
> -    assert(0);
> -}
> -
> -void helper_svm_check_intercept_param(CPUX86State *env, uint32_t type,
> -                                      uint64_t param)
> -{
> -}
> -
> -void cpu_svm_check_intercept_param(CPUX86State *env, uint32_t type,
> -                                   uint64_t param, uintptr_t retaddr)
> -{
> -}
> -
> -void helper_svm_check_io(CPUX86State *env, uint32_t port, uint32_t param,
> -                         uint32_t next_eip_addend)
> -{
> -}
> -#else
> -
>  static inline void svm_save_seg(CPUX86State *env, hwaddr addr,
>                                  const SegmentCache *sc)
>  {
> @@ -797,5 +741,3 @@ void do_vmexit(CPUX86State *env, uint32_t exit_code, uint64_t exit_info_1)
>         host's code segment or non-canonical (in the case of long mode), a
>         #GP fault is delivered inside the host. */
>  }
> -
> -#endif
> diff --git a/target/i386/tcg/user/svm_stubs.c b/target/i386/tcg/user/svm_stubs.c
> new file mode 100644
> index 0000000000..97528b56ad
> --- /dev/null
> +++ b/target/i386/tcg/user/svm_stubs.c
> @@ -0,0 +1,76 @@
> +/*
> + *  x86 SVM helpers (user-mode)
> + *
> + *  Copyright (c) 2003 Fabrice Bellard
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2.1 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "cpu.h"
> +#include "exec/helper-proto.h"
> +#include "tcg/helper-tcg.h"
> +
> +void helper_vmrun(CPUX86State *env, int aflag, int next_eip_addend)
> +{
> +}
> +
> +void helper_vmmcall(CPUX86State *env)
> +{
> +}
> +
> +void helper_vmload(CPUX86State *env, int aflag)
> +{
> +}
> +
> +void helper_vmsave(CPUX86State *env, int aflag)
> +{
> +}
> +
> +void helper_stgi(CPUX86State *env)
> +{
> +}
> +
> +void helper_clgi(CPUX86State *env)
> +{
> +}
> +
> +void helper_skinit(CPUX86State *env)
> +{
> +}
> +
> +void helper_invlpga(CPUX86State *env, int aflag)
> +{
> +}
> +
> +void cpu_vmexit(CPUX86State *nenv, uint32_t exit_code, uint64_t exit_info_1,
> +                uintptr_t retaddr)
> +{
> +    assert(0);
> +}
> +
> +void helper_svm_check_intercept_param(CPUX86State *env, uint32_t type,
> +                                      uint64_t param)
> +{
> +}
> +
> +void cpu_svm_check_intercept_param(CPUX86State *env, uint32_t type,
> +                                   uint64_t param, uintptr_t retaddr)
> +{
> +}
> +
> +void helper_svm_check_io(CPUX86State *env, uint32_t port, uint32_t param,
> +                         uint32_t next_eip_addend)
> +{
> +}
> diff --git a/target/i386/tcg/meson.build b/target/i386/tcg/meson.build
> index ec5daa1edc..6fbac2f240 100644
> --- a/target/i386/tcg/meson.build
> +++ b/target/i386/tcg/meson.build
> @@ -8,7 +8,6 @@ i386_ss.add(when: 'CONFIG_TCG', if_true: files(
>    'misc_helper.c',
>    'mpx_helper.c',
>    'seg_helper.c',
> -  'svm_helper.c',
>    'tcg-cpu.c',
>    'translate.c'), if_false: files('tcg-stub.c'))
>  
> diff --git a/target/i386/tcg/softmmu/meson.build b/target/i386/tcg/softmmu/meson.build
> index f84519a213..126528d0c9 100644
> --- a/target/i386/tcg/softmmu/meson.build
> +++ b/target/i386/tcg/softmmu/meson.build
> @@ -5,4 +5,5 @@ i386_softmmu_ss.add(when: ['CONFIG_TCG', 'CONFIG_SOFTMMU'], if_true: files(
>    'bpt_helper.c',
>    'misc_helper.c',
>    'fpu_helper.c',
> +  'svm_helper.c',
>  ))
> diff --git a/target/i386/tcg/user/meson.build b/target/i386/tcg/user/meson.build
> index 30eec3f5a4..c540ca2174 100644
> --- a/target/i386/tcg/user/meson.build
> +++ b/target/i386/tcg/user/meson.build
> @@ -2,4 +2,5 @@ i386_user_ss.add(when: ['CONFIG_TCG', 'CONFIG_USER_ONLY'], if_true: files(
>    'excp_helper.c',
>    'misc_helper.c',
>    'fpu_helper.c',
> +  'svm_stubs.c',
>  ))
>