| Message ID | 20210707204249.3046665-2-sathyanarayanan.kuppuswamy@linux.intel.com (mailing list archive) |
|---|---|
| State | Deferred, archived |
| Headers | show |
| Series | Add TDX Guest Support (Attestation support) | expand |
On 7/8/2021 4:42 AM, Kuppuswamy Sathyanarayanan wrote: > The TDX Guest-Host Communication Interface (GHCI) includes a module > call (TDREPORT TDCALL) that a guest can make to acquire a copy of the > attestation data that it needs to verify its trustworthiness. > > Add a wrapper function tdx_mcall_tdreport() that makes the module > call to get this data. > > See GHCI section 2.4.5 "TDCALL [TDG.MR.REPORT] leaf" for additional > details. > > [Xiaoyao: Proposed error code fix] > Reviewed-by: Tony Luck <tony.luck@intel.com> > Reviewed-by: Andi Kleen <ak@linux.intel.com> > Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> > --- > arch/x86/include/asm/tdx.h | 2 ++ > arch/x86/kernel/tdx.c | 33 +++++++++++++++++++++++++++++++++ > 2 files changed, 35 insertions(+) > > diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h > index 48927fac9e12..4f1b5c14a09b 100644 > --- a/arch/x86/include/asm/tdx.h > +++ b/arch/x86/include/asm/tdx.h > @@ -96,6 +96,8 @@ extern int tdx_hcall_gpa_intent(phys_addr_t gpa, int numpages, > > bool tdg_filter_enabled(void); > > +int tdx_mcall_tdreport(u64 data, u64 reportdata); > + > /* > * To support I/O port access in decompressor or early kernel init > * code, since #VE exception handler cannot be used, use paravirt > diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c > index f76af7661046..0f797803f4c8 100644 > --- a/arch/x86/kernel/tdx.c > +++ b/arch/x86/kernel/tdx.c > @@ -23,6 +23,7 @@ > /* TDX Module call Leaf IDs */ > #define TDINFO 1 > #define TDGETVEINFO 3 > +#define TDREPORT 4 > #define TDACCEPTPAGE 6 > > /* TDX hypercall Leaf IDs */ > @@ -30,6 +31,11 @@ > > /* TDX Module call error codes */ > #define TDX_PAGE_ALREADY_ACCEPTED 0x8000000000000001 > +#define TDCALL_RETURN_CODE_MASK 0xFFFFFFFF00000000 > +#define TDCALL_OPERAND_BUSY 0x8000020000000000 > +#define TDCALL_INVALID_OPERAND 0x8000000000000000 > +#define TDCALL_RETURN_CODE(a) ((a) & TDCALL_RETURN_CODE_MASK) > + > > #define VE_IS_IO_OUT(exit_qual) (((exit_qual) & 8) ? 0 : 1) > #define VE_GET_IO_SIZE(exit_qual) (((exit_qual) & 7) + 1) > @@ -139,6 +145,33 @@ static bool tdg_perfmon_enabled(void) > return td_info.attributes & BIT(63); > } > > +/* > + * tdx_mcall_tdreport() - Generate TDREPORT_STRUCT using TDCALL. > + * > + * @data : Physical address of 1024B aligned data to store > + * TDREPORT_STRUCT. > + * @reportdata : Physical address of 64B aligned report data > + * > + * return 0 on success or failure error number. > + */ > +int tdx_mcall_tdreport(u64 data, u64 reportdata) > +{ > + u64 ret; > + > + if (!data || !reportdata || !prot_guest_has(PR_GUEST_TDX)) > + return -EINVAL; > + > + ret = __trace_tdx_module_call(TDREPORT, data, reportdata, 0, 0, NULL); > + > + if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND) > + return -EINVAL; > + else if (TDCALL_RETURN_CODE(ret) == TDCALL_OPERAND_BUSY) > + return -EBUSY; Sorry I guess I didn't state it clearly during internal review. I suggest something like this if (ret != TDCALL_SUCCESS) { if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND) return -EINVAL; else if (TDCALL_RETURN_CODE(ret) == TDCALL_OPERAND_BUSY) return -EBUSY; else return -EFAULT; //I'm not sure if -EFAULT is proper. } > + return 0; > +} > +EXPORT_SYMBOL_GPL(tdx_mcall_tdreport); > + > static void tdg_get_info(void) > { > u64 ret; >
On 7/8/21 1:16 AM, Xiaoyao Li wrote: > > Sorry I guess I didn't state it clearly during internal review. > > I suggest something like this > > if (ret != TDCALL_SUCCESS) { > if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND) > return -EINVAL; > else if (TDCALL_RETURN_CODE(ret) == TDCALL_OPERAND_BUSY) > return -EBUSY; > else > return -EFAULT; //I'm not sure if -EFAULT is proper. > } As per current spec, TDCALL_INVALID_OPERAND, TDCALL_OPERAND_BUSY and 0 are the only possible return values. So I have checked for failure case in if condition and returned success by default. Any reason for specifically checking for success code ?
Hi, On 7/8/21 4:07 PM, Kuppuswamy, Sathyanarayanan wrote: > > > On 7/8/21 1:16 AM, Xiaoyao Li wrote: >> >> Sorry I guess I didn't state it clearly during internal review. >> >> I suggest something like this >> >> if (ret != TDCALL_SUCCESS) { >> if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND) >> return -EINVAL; >> else if (TDCALL_RETURN_CODE(ret) == TDCALL_OPERAND_BUSY) >> return -EBUSY; >> else >> return -EFAULT; //I'm not sure if -EFAULT is proper. >> } > > As per current spec, TDCALL_INVALID_OPERAND, TDCALL_OPERAND_BUSY and > 0 are the only possible return values. So I have checked for failure case > in if condition and returned success by default. Any reason for specifically > checking for success code ? Yes, new error codes might be introduced and you might forget to update this (or other) checks. Checking for errors really MUST always be done by checking for ret != success (typically ret != 0 or ret < 0). Only checking for known error codes means that if somehow an unknown error code gets thrown this gets treated as success, which is not acceptable behavior. Regards, Hans
On 7/8/21 7:20 AM, Hans de Goede wrote: > Yes, new error codes might be introduced and you might forget to > update this (or other) checks. > > Checking for errors really MUST always be done by checking for > ret != success (typically ret != 0 or ret < 0). > > Only checking for known error codes means that if somehow an > unknown error code gets thrown this gets treated as success, > which is not acceptable behavior. Got it. I will include this change in next version.
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h index 48927fac9e12..4f1b5c14a09b 100644 --- a/arch/x86/include/asm/tdx.h +++ b/arch/x86/include/asm/tdx.h @@ -96,6 +96,8 @@ extern int tdx_hcall_gpa_intent(phys_addr_t gpa, int numpages, bool tdg_filter_enabled(void); +int tdx_mcall_tdreport(u64 data, u64 reportdata); + /* * To support I/O port access in decompressor or early kernel init * code, since #VE exception handler cannot be used, use paravirt diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c index f76af7661046..0f797803f4c8 100644 --- a/arch/x86/kernel/tdx.c +++ b/arch/x86/kernel/tdx.c @@ -23,6 +23,7 @@ /* TDX Module call Leaf IDs */ #define TDINFO 1 #define TDGETVEINFO 3 +#define TDREPORT 4 #define TDACCEPTPAGE 6 /* TDX hypercall Leaf IDs */ @@ -30,6 +31,11 @@ /* TDX Module call error codes */ #define TDX_PAGE_ALREADY_ACCEPTED 0x8000000000000001 +#define TDCALL_RETURN_CODE_MASK 0xFFFFFFFF00000000 +#define TDCALL_OPERAND_BUSY 0x8000020000000000 +#define TDCALL_INVALID_OPERAND 0x8000000000000000 +#define TDCALL_RETURN_CODE(a) ((a) & TDCALL_RETURN_CODE_MASK) + #define VE_IS_IO_OUT(exit_qual) (((exit_qual) & 8) ? 0 : 1) #define VE_GET_IO_SIZE(exit_qual) (((exit_qual) & 7) + 1) @@ -139,6 +145,33 @@ static bool tdg_perfmon_enabled(void) return td_info.attributes & BIT(63); } +/* + * tdx_mcall_tdreport() - Generate TDREPORT_STRUCT using TDCALL. + * + * @data : Physical address of 1024B aligned data to store + * TDREPORT_STRUCT. + * @reportdata : Physical address of 64B aligned report data + * + * return 0 on success or failure error number. + */ +int tdx_mcall_tdreport(u64 data, u64 reportdata) +{ + u64 ret; + + if (!data || !reportdata || !prot_guest_has(PR_GUEST_TDX)) + return -EINVAL; + + ret = __trace_tdx_module_call(TDREPORT, data, reportdata, 0, 0, NULL); + + if (TDCALL_RETURN_CODE(ret) == TDCALL_INVALID_OPERAND) + return -EINVAL; + else if (TDCALL_RETURN_CODE(ret) == TDCALL_OPERAND_BUSY) + return -EBUSY; + + return 0; +} +EXPORT_SYMBOL_GPL(tdx_mcall_tdreport); + static void tdg_get_info(void) { u64 ret;