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Peter Anvin" , Dave Hansen , linux-kernel@vger.kernel.org, virtualization@lists.linux.dev, bp@alien8.de, dave.hansen@linux.intel.com, mingo@redhat.com, tglx@linutronix.de Cc: x86@kernel.org, netdev@vger.kernel.org, richardcochran@gmail.com, linux-input@vger.kernel.org, dmitry.torokhov@gmail.com, zackr@vmware.com, linux-graphics-maintainer@vmware.com, pv-drivers@vmware.com, namit@vmware.com, timothym@vmware.com, akaher@vmware.com, jsipek@vmware.com, dri-devel@lists.freedesktop.org, daniel@ffwll.ch, airlied@gmail.com, tzimmermann@suse.de, mripard@kernel.org, maarten.lankhorst@linux.intel.com, horms@kernel.org, kirill.shutemov@linux.intel.com References: <20240109084052.58661-1-amakhalov@vmware.com> <20240109084052.58661-8-amakhalov@vmware.com> <4CF87BC4-E8C8-4584-A275-5A985D5A18A1@zytor.com> Content-Language: en-US From: Alexey Makhalov Autocrypt: addr=alexey.makhalov@broadcom.com; keydata= xsFNBGVo9lkBEACeouRIm6Q3QTvjcnPczfBqgLffURstVJz5nqjnrNR4T+8dwNrZB8PTgOWA QdGV4bIyqtNG7UHQuZ7sVKr2tx0gYJyQ5uZgncEHB5YIuhQ/CyAHrVmO+5/0/xWCLI0g44rF ZJqsYw2JQ2+vayTWbR65rkOiKL8GOVFNZanDg80BRh6qCmCEMXd/tymxvgnvWpHtxMgukexk 4vV9nV4XhxRVYdpLk8mBxsh+AEbHE+nbWgIuJDrmrZDGI2Dha7JFoB0Mi6hbbYd9BdkcHKQ7 6c+S1xOrZL3jX7OIFhb4NNnEOhh8/+BDlyby478p6YsimNa7TgAUbrygGyfVG8usrZy8SvO+ vUbVQwqjcJaCK1xazK12dfuZm2kSMJUrJqa9ng6OMjkE2/WrtnK8ruFNSCdytzbuheT0nYUJ Uwy84cU4p2K/N2C4vYjcn+IT+l1BFr5FViKYruoRLVH6zK/WOoZjA+Fc6tdM5nC1pgSB9c7h XLQqDSzYPzk3nqeHWG1qJ0Hu7pscIrjxyNTIZ5le0TlpblJdoRcL5maDNw22yle8m4D18ERF VrqNoqwW8fObMCHbd6C3m75lzerq1HhrSvLyU4UfprEyAcjOI1C0319SXfYlXDjKXRQyaDZP wxln8uShSitSSnx0AsSAjcUa8Cc7km81+G2WSK3S2wVIAN11awARAQABzS5BbGV4ZXkgTWFr aGFsb3YgPGFsZXhleS5tYWtoYWxvdkBicm9hZGNvbS5jb20+wsGNBBMBCAA3FiEEjLzRtST/ a5u42vOKbM7yHr5SJ3cFAmVo9lwFCQ0oaIACGwMECwkIBwUVCAkKCwUWAgMBAAAKCRBszvIe vlInd0jTD/9bZtjehewLRrW3dRDAbLG/+J5g1K4X5qQPfAo42NrhZQlOTibL7ixwq7NSXynZ V4Iu9jHAW++KXjxJzkg7zjBf9OOvvgCpqZGKYgWNvHHnX4eIVh8Ikp5JtvGPMBcRv7lJA5co kb+RHo9iRrB1dvRIOsP1SlGS85SiNA0yvmgqwbigLDmDRSWtvvt9XPwU1iqF+1OopT3UE10i /z+qE2ogcw2ADveBovq2W4JeQEBvlETwDKOdh8Q3UBHOqrZUrL7YjpUxgmb89FcjdDzUU95I fCB5YxF0hUctxFH5Uujh2F4qk0m2rp7+aOGtxWCJUqkHXjgpOoxyn0FPZiZlDkst84NO5OSI 5ZFPwaFqxUrFF+cFCY2O/UE2gpoK9Lt3gYNK6o2WIAtufuiYVdK6lANMkBgZ+t2fDLIN147a 172zu8XnyJMTo+tVfUjxwqynoR/NSWpVPs0Ck3K0LGjQE0tJ6HZrH0vudXk3YaiqW+D4CtGh I17Pk0h6x8LCdjmWmuDXoc99ezOEFSyWuTHjAYxx3cmgSUyIhdHtimuf0CVLTcFoBErb/5pJ zjb11Cj0HP87FMH57bnD3qyfkBMOB6tztfdt3vkCBaWkxaiTGXNhwr4IiLUoi90yIdXDMcTj /gvnjXgN+31iYgPWgTOdUEQud0DwDwuDwkzx/0x4sF1Dfc7BTQRlaPZcARAAuGkoYKWcrCh8 5RffedM6uBZ4p5Z4+RVj05uq7hlAwhHUpLP/XGbgNzhJP375Lonmnuyg2x7oHxfiwOohuuiA MnhSeEXn2qWZJuHosrYxs9y2zyiE/GTUAcqKiYBFa/96zOaZjHpNuQ5qSHYL64WhqvtmCQYg fL+jes2Z4IXl2R7MrN9OE+G3A3pOAo8TZKUEmlUV85fSmgopIX+hCiSQmRNRtp2jK6hd2+38 YAXc+eRxYgXKaWX5zeBgNrfM7Oxeh/0iWRZPWstTvVH2xMlzywOB3e/fqg+Q3NlPGDrTyHoc L86ZELSLcMTFn+RXw8lX8oVjTcQA0M8sQHB5g0JEWtMsFjnQZkJGCfeh0Odbn/F8nZ6LQQtu +fjc/4n9vRun+PZjdhd3W9ZM9D87W9XJg9txIaYnoUXBLLpHK/OirFfr5cJTUf4svtE3EVXb x6P9vr7zqUbE0f76h1eDPmyMwFAuibIXhNoEoKQtEjLX9aKgKYny3hczRiuQpA+6U4oTNn4S /CEqphLPT53aMH0w4x0CebMPozf24ZE9YphdX8ECclLBlDL1/zx2xKrJNw8v6wdXMSfsybBW 98b5b1eVBk1uc1UMlpDl7AIHyCMTjL9Ha85eoya/Hk9l93aVHgK04hOBY2ED1/ZRpj0M5P5m tNX1JqZunpyvKooT1PrJr4UAEQEAAcLBfAQYAQgAJhYhBIy80bUk/2ubuNrzimzO8h6+Uid3 BQJlaPZeBQkNKGiAAhsMAAoJEGzO8h6+Uid3SDoQAI3XXqsehWKvyAVeGXPxmkk+Suos/nJC xZWjp4U2xbbegBnNWladZoNdlVW/WV+FSFsN5IWztxQTWBMI12A0dx+Ooi9PSIANnlN+gQsA 9WeQ5iDNveEHZyK1GmuqZ3M3YZ1r3T2KyzTnPPZQ1B8gMQ442bOBWe077MqtLaC0J1jHyWHU j6BbUCAyR2/OCV/n1bH4wYIm2lgrOd2WuzoAGvju+j2g7hMRxw/xeHeu8S0czHuEZ0dC6fR1 ZKUOw03+mM/xRzL1be6RVS9AF7R5oDd11RrTOb7k14z0inFqSRrRwzOPKcuMxrApcquar336 3FQuLcJLjBo/SAOh2JatOkkwkw5PZseqdwcAk5+wcCbdYy8J8ttR04iV1FzrdQp8HbVxGNo7 AlDn1qtoHzvJHSQG51tbXWfLIi1ek3tpwJWj08+Zo+M47X6B65g7wdrwCiiFfclhXhI1eJNy fqqZgi3rxgu4sc5lmR846emZ/Tx85/nizqWCv7xUBxQwmhRPZRW+37vS2OLpyrTtBj3/tEM9 m9GMmTZqaJFeK7WCpprJV4jNHpWZuNAsQrdK1MrceIxb0/6wYe0xK79lScxms+zs9pGTrO4U 5RoS4gXK65ECcBH8/mumV6oBmLrNxKUrzTczdo9PnkmRyZcAa6AndbjmQDznwxvTZu2LjMPC EuY0 In-Reply-To: <4CF87BC4-E8C8-4584-A275-5A985D5A18A1@zytor.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 1/22/24 10:28 AM, H. Peter Anvin wrote: > On January 22, 2024 8:32:22 AM PST, Dave Hansen wrote: >> On 1/9/24 00:40, Alexey Makhalov wrote: >>> +#ifdef CONFIG_INTEL_TDX_GUEST >>> +unsigned long vmware_tdx_hypercall(unsigned long cmd, >>> + struct tdx_module_args *args) >>> +{ >>> + if (!hypervisor_is_type(X86_HYPER_VMWARE)) >>> + return ULONG_MAX; >>> + >>> + if (cmd & ~VMWARE_CMD_MASK) { >>> + pr_warn_once("Out of range command %lx\n", cmd); >>> + return ULONG_MAX; >>> + } >>> + >>> + args->r10 = VMWARE_TDX_VENDOR_LEAF; >>> + args->r11 = VMWARE_TDX_HCALL_FUNC; >>> + args->r12 = VMWARE_HYPERVISOR_MAGIC; >>> + args->r13 = cmd; >>> + args->r15 = 0; /* CPL */ >>> + >>> + __tdx_hypercall(args); >>> + >>> + return args->r12; >>> +} >>> +EXPORT_SYMBOL_GPL(vmware_tdx_hypercall); >>> +#endif >> >> This is the kind of wrapper that I was hoping for. Thanks. >> >> Acked-by: Dave Hansen >> > > I'm slightly confused by this TBH. > > Why are the arguments passed in as a structure, which is modified by the wrapper to boot? This is analogous to a system call interface. > > Furthermore, this is an out-of-line function; it should never be called with !X86_HYPER_VMWARE or you are introducing overhead for other hypervisors; I believe a pr_warn_once() is in order at least, just as you have for the out-of-range test. > This patch series introduces vmware_hypercall family of functions similar to kvm_hypercall. Similarity: both vmware and kvm implementations are static inline functions and both of them use __tdx_hypercall (global not exported symbol). Difference: kvm_hypercall functions are used _only_ within the kernel, but vmware_hypercall are also used by modules. Exporting __tdx_hypercall function is an original Dave's concern. So we ended up with exporting wrapper, not generic, but VMware specific with added checks against arbitrary use. vmware_tdx_hypercall is not designed for !X86_HYPER_VMWARE callers. But such a calls are not forbidden. Arguments in a structure is an API for __tdx_hypercall(). Input and output argument handling are done by vmware_hypercall callers, while VMware specific dress up is inside the wrapper. Peter, do you think code comments are required to make it clear for the reader?