| Message ID | d307d82a52ef604cfff8c7745ad8613d3ddfa0c8.1721186590.git.kai.huang@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | TDX host: metadata reading tweaks, bug fix and info dump | expand |
Kai Huang wrote: > Old TDX modules can clobber RBP in the TDH.VP.ENTER SEAMCALL. However > RBP is used as frame pointer in the x86_64 calling convention, and > clobbering RBP could result in bad things like being unable to unwind > the stack if any non-maskable exceptions (NMI, #MC etc) happens in that > gap. > > A new "NO_RBP_MOD" feature was introduced to more recent TDX modules to > not clobber RBP. This feature is reported in the TDX_FEATURES0 global > metadata field via bit 18. > > Don't initialize the TDX module if this feature is not supported [1]. > > Link: https://lore.kernel.org/all/c0067319-2653-4cbd-8fee-1ccf21b1e646@suse.com/T/#mef98469c51e2382ead2c537ea189752360bd2bef [1] > Signed-off-by: Kai Huang <kai.huang@intel.com> > Reviewed-by: Nikolay Borisov <nik.borisov@suse.com> > --- > > v1 -> v2: > - Add tag from Nikolay. > > --- > arch/x86/virt/vmx/tdx/tdx.c | 17 +++++++++++++++++ > arch/x86/virt/vmx/tdx/tdx.h | 1 + > 2 files changed, 18 insertions(+) > > diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c > index 3c19295f1f8f..ec6156728423 100644 > --- a/arch/x86/virt/vmx/tdx/tdx.c > +++ b/arch/x86/virt/vmx/tdx/tdx.c > @@ -484,6 +484,18 @@ static int get_tdx_sysinfo(struct tdx_sysinfo *sysinfo) > return get_tdx_tdmr_sysinfo(&sysinfo->tdmr_info); > } > > +static int check_module_compatibility(struct tdx_sysinfo *sysinfo) How about check_features()? Almost everything having to do with TDX concerns the TDX module, so using "module" in a symbol name rarely adds any useful context. > +{ > + u64 tdx_features0 = sysinfo->module_info.tdx_features0; > + > + if (!(tdx_features0 & TDX_FEATURES0_NO_RBP_MOD)) { > + pr_err("NO_RBP_MOD feature is not supported\n"); A user would have no idea with this error message how about something like: pr_err("frame pointer (RBP) clobber bug present, upgrade TDX module\n");
On Mon, 2024-08-05 at 21:55 -0700, Williams, Dan J wrote: > Kai Huang wrote: > > Old TDX modules can clobber RBP in the TDH.VP.ENTER SEAMCALL. However > > RBP is used as frame pointer in the x86_64 calling convention, and > > clobbering RBP could result in bad things like being unable to unwind > > the stack if any non-maskable exceptions (NMI, #MC etc) happens in that > > gap. > > > > A new "NO_RBP_MOD" feature was introduced to more recent TDX modules to > > not clobber RBP. This feature is reported in the TDX_FEATURES0 global > > metadata field via bit 18. > > > > Don't initialize the TDX module if this feature is not supported [1]. > > > > Link: https://lore.kernel.org/all/c0067319-2653-4cbd-8fee-1ccf21b1e646@suse.com/T/#mef98469c51e2382ead2c537ea189752360bd2bef [1] > > Signed-off-by: Kai Huang <kai.huang@intel.com> > > Reviewed-by: Nikolay Borisov <nik.borisov@suse.com> > > --- > > > > v1 -> v2: > > - Add tag from Nikolay. > > > > --- > > arch/x86/virt/vmx/tdx/tdx.c | 17 +++++++++++++++++ > > arch/x86/virt/vmx/tdx/tdx.h | 1 + > > 2 files changed, 18 insertions(+) > > > > diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c > > index 3c19295f1f8f..ec6156728423 100644 > > --- a/arch/x86/virt/vmx/tdx/tdx.c > > +++ b/arch/x86/virt/vmx/tdx/tdx.c > > @@ -484,6 +484,18 @@ static int get_tdx_sysinfo(struct tdx_sysinfo *sysinfo) > > return get_tdx_tdmr_sysinfo(&sysinfo->tdmr_info); > > } > > > > +static int check_module_compatibility(struct tdx_sysinfo *sysinfo) > > How about check_features()? Almost everything having to do with TDX > concerns the TDX module, so using "module" in a symbol name rarely adds > any useful context. Yeah fine to me. Will do. > > > +{ > > + u64 tdx_features0 = sysinfo->module_info.tdx_features0; > > + > > + if (!(tdx_features0 & TDX_FEATURES0_NO_RBP_MOD)) { > > + pr_err("NO_RBP_MOD feature is not supported\n"); > > A user would have no idea with this error message how about something > like: > > pr_err("frame pointer (RBP) clobber bug present, upgrade TDX module\n"); Yeah this is certainly better. Will do. Thanks!
diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c index 3c19295f1f8f..ec6156728423 100644 --- a/arch/x86/virt/vmx/tdx/tdx.c +++ b/arch/x86/virt/vmx/tdx/tdx.c @@ -484,6 +484,18 @@ static int get_tdx_sysinfo(struct tdx_sysinfo *sysinfo) return get_tdx_tdmr_sysinfo(&sysinfo->tdmr_info); } +static int check_module_compatibility(struct tdx_sysinfo *sysinfo) +{ + u64 tdx_features0 = sysinfo->module_info.tdx_features0; + + if (!(tdx_features0 & TDX_FEATURES0_NO_RBP_MOD)) { + pr_err("NO_RBP_MOD feature is not supported\n"); + return -EINVAL; + } + + return 0; +} + /* Calculate the actual TDMR size */ static int tdmr_size_single(u16 max_reserved_per_tdmr) { @@ -1266,6 +1278,11 @@ static int init_tdx_module(void) print_basic_sysinfo(&sysinfo); + /* Check whether the kernel can support this module */ + ret = check_module_compatibility(&sysinfo); + if (ret) + return ret; + /* * To keep things simple, assume that all TDX-protected memory * will come from the page allocator. Make sure all pages in the diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h index 4b43eb774ffa..20fd7cb5937a 100644 --- a/arch/x86/virt/vmx/tdx/tdx.h +++ b/arch/x86/virt/vmx/tdx/tdx.h @@ -148,6 +148,7 @@ struct tdx_sysinfo_module_info { }; #define TDX_SYS_ATTR_DEBUG_MODULE 0x1 +#define TDX_FEATURES0_NO_RBP_MOD _BITULL(18) /* Class "TDX Module Version" */ struct tdx_sysinfo_module_version {