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Peter Anvin" , Paolo Bonzini , Wanpeng Li , Vitaly Kuznetsov , Andy Lutomirski , Frederic Weisbecker , "Paul E. McKenney" , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes , Josh Poimboeuf , Jason Baron , Kees Cook , Sami Tolvanen , Ard Biesheuvel , Nicholas Piggin , Juerg Haefliger , Nicolas Saenz Julienne , "Kirill A. Shutemov" , Nadav Amit , Dan Carpenter , Chuang Wang , Yang Jihong , Petr Mladek , "Jason A. Donenfeld" , Song Liu , Julian Pidancet , Tom Lendacky , Dionna Glaze , =?UTF-8?Q?Thomas_Wei=C3=9Fschuh?= , Juri Lelli , Marcelo Tosatti , Yair Podemsky , Daniel Wagner , Petr Tesarik References: <20241119153502.41361-1-vschneid@redhat.com> <20241119153502.41361-14-vschneid@redhat.com> <20241120152216.GM19989@noisy.programming.kicks-ass.net> <20241120153221.GM38972@noisy.programming.kicks-ass.net> <20241121111221.GE24774@noisy.programming.kicks-ass.net> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; keydata= xsFNBE6HMP0BEADIMA3XYkQfF3dwHlj58Yjsc4E5y5G67cfbt8dvaUq2fx1lR0K9h1bOI6fC oAiUXvGAOxPDsB/P6UEOISPpLl5IuYsSwAeZGkdQ5g6m1xq7AlDJQZddhr/1DC/nMVa/2BoY 2UnKuZuSBu7lgOE193+7Uks3416N2hTkyKUSNkduyoZ9F5twiBhxPJwPtn/wnch6n5RsoXsb ygOEDxLEsSk/7eyFycjE+btUtAWZtx+HseyaGfqkZK0Z9bT1lsaHecmB203xShwCPT49Blxz VOab8668QpaEOdLGhtvrVYVK7x4skyT3nGWcgDCl5/Vp3TWA4K+IofwvXzX2ON/Mj7aQwf5W iC+3nWC7q0uxKwwsddJ0Nu+dpA/UORQWa1NiAftEoSpk5+nUUi0WE+5DRm0H+TXKBWMGNCFn c6+EKg5zQaa8KqymHcOrSXNPmzJuXvDQ8uj2J8XuzCZfK4uy1+YdIr0yyEMI7mdh4KX50LO1 pmowEqDh7dLShTOif/7UtQYrzYq9cPnjU2ZW4qd5Qz2joSGTG9eCXLz5PRe5SqHxv6ljk8mb ApNuY7bOXO/A7T2j5RwXIlcmssqIjBcxsRRoIbpCwWWGjkYjzYCjgsNFL6rt4OL11OUF37wL QcTl7fbCGv53KfKPdYD5hcbguLKi/aCccJK18ZwNjFhqr4MliQARAQABzUVEYXZpZCBDaHJp c3RvcGhlciBIYW5zZW4gKEludGVsIFdvcmsgQWRkcmVzcykgPGRhdmUuaGFuc2VuQGludGVs LmNvbT7CwXgEEwECACIFAlQ+9J0CGwMGCwkIBwMCBhUIAgkKCwQWAgMBAh4BAheAAAoJEGg1 lTBwyZKwLZUP/0dnbhDc229u2u6WtK1s1cSd9WsflGXGagkR6liJ4um3XCfYWDHvIdkHYC1t MNcVHFBwmQkawxsYvgO8kXT3SaFZe4ISfB4K4CL2qp4JO+nJdlFUbZI7cz/Td9z8nHjMcWYF IQuTsWOLs/LBMTs+ANumibtw6UkiGVD3dfHJAOPNApjVr+M0P/lVmTeP8w0uVcd2syiaU5jB aht9CYATn+ytFGWZnBEEQFnqcibIaOrmoBLu2b3fKJEd8Jp7NHDSIdrvrMjYynmc6sZKUqH2 I1qOevaa8jUg7wlLJAWGfIqnu85kkqrVOkbNbk4TPub7VOqA6qG5GCNEIv6ZY7HLYd/vAkVY E8Plzq/NwLAuOWxvGrOl7OPuwVeR4hBDfcrNb990MFPpjGgACzAZyjdmYoMu8j3/MAEW4P0z F5+EYJAOZ+z212y1pchNNauehORXgjrNKsZwxwKpPY9qb84E3O9KYpwfATsqOoQ6tTgr+1BR CCwP712H+E9U5HJ0iibN/CDZFVPL1bRerHziuwuQuvE0qWg0+0SChFe9oq0KAwEkVs6ZDMB2 P16MieEEQ6StQRlvy2YBv80L1TMl3T90Bo1UUn6ARXEpcbFE0/aORH/jEXcRteb+vuik5UGY 5TsyLYdPur3TXm7XDBdmmyQVJjnJKYK9AQxj95KlXLVO38lczsFNBFRjzmoBEACyAxbvUEhd GDGNg0JhDdezyTdN8C9BFsdxyTLnSH31NRiyp1QtuxvcqGZjb2trDVuCbIzRrgMZLVgo3upr MIOx1CXEgmn23Zhh0EpdVHM8IKx9Z7V0r+rrpRWFE8/wQZngKYVi49PGoZj50ZEifEJ5qn/H Nsp2+Y+bTUjDdgWMATg9DiFMyv8fvoqgNsNyrrZTnSgoLzdxr89FGHZCoSoAK8gfgFHuO54B lI8QOfPDG9WDPJ66HCodjTlBEr/Cwq6GruxS5i2Y33YVqxvFvDa1tUtl+iJ2SWKS9kCai2DR 3BwVONJEYSDQaven/EHMlY1q8Vln3lGPsS11vSUK3QcNJjmrgYxH5KsVsf6PNRj9mp8Z1kIG qjRx08+nnyStWC0gZH6NrYyS9rpqH3j+hA2WcI7De51L4Rv9pFwzp161mvtc6eC/GxaiUGuH BNAVP0PY0fqvIC68p3rLIAW3f97uv4ce2RSQ7LbsPsimOeCo/5vgS6YQsj83E+AipPr09Caj 0hloj+hFoqiticNpmsxdWKoOsV0PftcQvBCCYuhKbZV9s5hjt9qn8CE86A5g5KqDf83Fxqm/ vXKgHNFHE5zgXGZnrmaf6resQzbvJHO0Fb0CcIohzrpPaL3YepcLDoCCgElGMGQjdCcSQ+Ci FCRl0Bvyj1YZUql+ZkptgGjikQARAQABwsFfBBgBAgAJBQJUY85qAhsMAAoJEGg1lTBwyZKw l4IQAIKHs/9po4spZDFyfDjunimEhVHqlUt7ggR1Hsl/tkvTSze8pI1P6dGp2XW6AnH1iayn yRcoyT0ZJ+Zmm4xAH1zqKjWplzqdb/dO28qk0bPso8+1oPO8oDhLm1+tY+cOvufXkBTm+whm +AyNTjaCRt6aSMnA/QHVGSJ8grrTJCoACVNhnXg/R0g90g8iV8Q+IBZyDkG0tBThaDdw1B2l asInUTeb9EiVfL/Zjdg5VWiF9LL7iS+9hTeVdR09vThQ/DhVbCNxVk+DtyBHsjOKifrVsYep WpRGBIAu3bK8eXtyvrw1igWTNs2wazJ71+0z2jMzbclKAyRHKU9JdN6Hkkgr2nPb561yjcB8 sIq1pFXKyO+nKy6SZYxOvHxCcjk2fkw6UmPU6/j/nQlj2lfOAgNVKuDLothIxzi8pndB8Jju KktE5HJqUUMXePkAYIxEQ0mMc8Po7tuXdejgPMwgP7x65xtfEqI0RuzbUioFltsp1jUaRwQZ MTsCeQDdjpgHsj+P2ZDeEKCbma4m6Ez/YWs4+zDm1X8uZDkZcfQlD9NldbKDJEXLIjYWo1PH hYepSffIWPyvBMBTW2W5FRjJ4vLRrJSUoEfJuPQ3vW9Y73foyo/qFoURHO48AinGPZ7PC7TF vUaNOTjKedrqHkaOcqB185ahG2had0xnFsDPlx5y In-Reply-To: <20241121111221.GE24774@noisy.programming.kicks-ass.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 096E314000F X-Stat-Signature: 351qm1ka7xgq536rf4kfa4cznxtpbdaq X-HE-Tag: 1732201630-363745 X-HE-Meta: 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 8RgNqBKs /gegmsef9uedMbrblb0jnykFbHN6GWrm/W+ln1mQPqmfMkdPvGGpZk44Kvt+A3iHm9lVi/MPLZmdC8yjtdJoj3tDxLr2IhUPe01wm+qZBpQeZL+R5BL9dmuGy9/JpxQoRI3urknkldy0w7HZw825Wa96AmpqtmvER3FxmY3Hd47RU4n7Dh4jWpTLeUh8AVZLexKwZLX3y74eKZZ37S7K4ExaZb4G4EbhBE8TiSY1b6bWMjuJfQMOjIJN/rs3tkzKzjCkc614IdAUWwLrSm1CDZ6PaJahXaTx4/Ab48k7jAKX47Vr7JEmydzRgLtNYosp22mwH X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 11/21/24 03:12, Peter Zijlstra wrote: >> I see e.g. ds_clear_cea() clears PTEs that can have the _PAGE_GLOBAL flag, >> and it correctly uses the non-deferrable flush_tlb_kernel_range(). > > I always forget what we use global pages for, dhansen might know, but > let me try and have a look. > > I *think* we only have GLOBAL on kernel text, and that only sometimes. I think you're remembering how _PAGE_GLOBAL gets used when KPTI is in play. Ignoring KPTI for a sec... We use _PAGE_GLOBAL for all kernel mappings. Before PCIDs, global mappings let the kernel TLB entries live across CR3 writes. When PCIDs are in play, global mappings let two different ASIDs share TLB entries. When KPTI is around, the kernel writes CR3 at user/kernel switches to make sure secrets are unmapped and can't be leaked by Meltdown. But unmapping those secrets doesn't do squat if they were mapped globally since they'll still be in the TLB and quite usable. There, we're more judicious and only mark performance-sensitive things that are not secret to be global, like kernel text.