| Message ID | cover.1684137557.git.houwenlong.hwl@antgroup.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | x86/fixmap: Unify FIXADDR_TOP | expand |
On Mon, May 15, 2023 at 04:19:31PM +0800, Hou Wenlong wrote: > This patchset unifies FIXADDR_TOP as a variable for x86, allowing the > fixmap area to be movable and relocated with the kernel image in the > x86/PIE patchset [0]. This enables the kernel image to be relocated in > the top 512G of the address space. > > [0] https://lore.kernel.org/lkml/cover.1682673542.git.houwenlong.hwl@antgroup.com > > Hou Wenlong (4): > x86/vsyscall: Don't use set_fixmap() to map vsyscall page > x86/xen: Pin up to VSYSCALL_ADDR when vsyscall page is out of fixmap > area > x86/fixmap: Move vsyscall page out of fixmap area > x86/fixmap: Unify FIXADDR_TOP > > arch/x86/entry/vsyscall/vsyscall_64.c | 7 +----- > arch/x86/include/asm/fixmap.h | 28 ++++------------------- > arch/x86/include/asm/paravirt.h | 7 ++++++ > arch/x86/include/asm/paravirt_types.h | 4 ++++ > arch/x86/include/asm/vsyscall.h | 13 +++++++++++ > arch/x86/kernel/head64.c | 1 - > arch/x86/kernel/head_64.S | 6 ++--- > arch/x86/kernel/paravirt.c | 4 ++++ > arch/x86/mm/dump_pagetables.c | 3 ++- > arch/x86/mm/fault.c | 1 - > arch/x86/mm/init_64.c | 2 +- > arch/x86/mm/ioremap.c | 5 ++--- > arch/x86/mm/pgtable.c | 13 +++++++++++ > arch/x86/mm/pgtable_32.c | 3 --- > arch/x86/xen/mmu_pv.c | 32 +++++++++++++++++++-------- > 15 files changed, 77 insertions(+), 52 deletions(-) > > > base-commit: f585d5177e1aad174fd6da0e3936b682ed58ced0 > -- > 2.31.1 Hi, Just wanted to send a kind ping on this patchset. Thanks.
On 5/15/23 01:19, Hou Wenlong wrote: > This patchset unifies FIXADDR_TOP as a variable for x86, allowing the > fixmap area to be movable and relocated with the kernel image in the > x86/PIE patchset [0]. This enables the kernel image to be relocated in > the top 512G of the address space. What problems does this patch set solve? How might that solution be visible to end users? Why is this problem important to you? Also, while you're waiting for someone to review _your_ code, have you considered reviewing anyone else's code? I don't think I've seen any review activity from you lately.
On Mon, May 15 2023 at 16:19, Hou Wenlong wrote: > This patchset unifies FIXADDR_TOP as a variable for x86, allowing the > fixmap area to be movable and relocated with the kernel image in the > x86/PIE patchset [0]. This enables the kernel image to be relocated in > the top 512G of the address space. What for? What's the use case. Please provide a proper argument why this is generally useful and important. Thanks, tglx
On Wed, Jun 07, 2023 at 08:49:15PM +0800, Dave Hansen wrote: > On 5/15/23 01:19, Hou Wenlong wrote: > > This patchset unifies FIXADDR_TOP as a variable for x86, allowing the > > fixmap area to be movable and relocated with the kernel image in the > > x86/PIE patchset [0]. This enables the kernel image to be relocated in > > the top 512G of the address space. > > What problems does this patch set solve? How might that solution be > visible to end users? Why is this problem important to you? > > Also, while you're waiting for someone to review _your_ code, have you > considered reviewing anyone else's code? I don't think I've seen any > review activity from you lately. Hello, Sorry for bothering you. This patch is not important; it is just a part of our PIE patchset. I should be more patient. We want to build the kernel as PIE and allow the kernel image area, including the fixmap area, to be placed at any virtual address. We have also implemented a PV Linux guest based on PIE, which can be used in software virtualization similar to Lguest. PIE makes the guest kernel share the host kernel space similar to a normal userspace process. Additionally, we are considering whether it is possible to use PIE and PVOPS to implement a user-mode kernel. Thank you for your advice. I will participate more actively in community review activities. Sorry again for bothering you. Thanks.
On Thu, Jun 08 2023 at 17:33, Hou Wenlong wrote: > On Wed, Jun 07, 2023 at 08:49:15PM +0800, Dave Hansen wrote: >> What problems does this patch set solve? How might that solution be >> visible to end users? Why is this problem important to you? > > We want to build the kernel as PIE and allow the kernel image area, > including the fixmap area, to be placed at any virtual address. You are still failing to tell us why you want that and which problem this solves. Just that fact that you want to something is not an argument. > We have also implemented a PV Linux guest based on PIE, which can be > used in software virtualization similar to Lguest. PIE makes the guest > kernel share the host kernel space similar to a normal userspace > process. Additionally, we are considering whether it is possible to > use PIE and PVOPS to implement a user-mode kernel. That solves what? Thanks, tglx
This patchset unifies FIXADDR_TOP as a variable for x86, allowing the fixmap area to be movable and relocated with the kernel image in the x86/PIE patchset [0]. This enables the kernel image to be relocated in the top 512G of the address space. [0] https://lore.kernel.org/lkml/cover.1682673542.git.houwenlong.hwl@antgroup.com Hou Wenlong (4): x86/vsyscall: Don't use set_fixmap() to map vsyscall page x86/xen: Pin up to VSYSCALL_ADDR when vsyscall page is out of fixmap area x86/fixmap: Move vsyscall page out of fixmap area x86/fixmap: Unify FIXADDR_TOP arch/x86/entry/vsyscall/vsyscall_64.c | 7 +----- arch/x86/include/asm/fixmap.h | 28 ++++------------------- arch/x86/include/asm/paravirt.h | 7 ++++++ arch/x86/include/asm/paravirt_types.h | 4 ++++ arch/x86/include/asm/vsyscall.h | 13 +++++++++++ arch/x86/kernel/head64.c | 1 - arch/x86/kernel/head_64.S | 6 ++--- arch/x86/kernel/paravirt.c | 4 ++++ arch/x86/mm/dump_pagetables.c | 3 ++- arch/x86/mm/fault.c | 1 - arch/x86/mm/init_64.c | 2 +- arch/x86/mm/ioremap.c | 5 ++--- arch/x86/mm/pgtable.c | 13 +++++++++++ arch/x86/mm/pgtable_32.c | 3 --- arch/x86/xen/mmu_pv.c | 32 +++++++++++++++++++-------- 15 files changed, 77 insertions(+), 52 deletions(-) base-commit: f585d5177e1aad174fd6da0e3936b682ed58ced0 -- 2.31.1