similar to: [patch 3/9] lguest: the host code

Hi, For some days I have been looking for the bug that causes an easily reproducible oops in the guest when I apply my PAE support _draft_ patch (appended at the end of this mail) to lguest. This is the oops: Setting kernel variables...done. Will now mount local filesystems:. Will now activate swapfile swap:done. Cleaning /tmp... [ 84.749676] BUG: unable to handle kernel NULL pointer

Hi, For some days I have been looking for the bug that causes an easily reproducible oops in the guest when I apply my PAE support _draft_ patch (appended at the end of this mail) to lguest. This is the oops: Setting kernel variables...done. Will now mount local filesystems:. Will now activate swapfile swap:done. Cleaning /tmp... [ 84.749676] BUG: unable to handle kernel NULL pointer

Hi, this version requires that host and guest have the same PAE status. NX cap is not offered to the guest, yet. Thanks, Matias Lguest PAE support Signed-off-by: Matias Zabaljauregui <zabaljauregui at gmail.com> --- Documentation/lguest/lguest.txt | 1 - arch/x86/include/asm/lguest.h | 7 +- arch/x86/include/asm/lguest_hcall.h | 3 +- arch/x86/lguest/Kconfig

Hi, this version requires that host and guest have the same PAE status. NX cap is not offered to the guest, yet. Thanks, Matias Lguest PAE support Signed-off-by: Matias Zabaljauregui <zabaljauregui at gmail.com> --- Documentation/lguest/lguest.txt | 1 - arch/x86/include/asm/lguest.h | 7 +- arch/x86/include/asm/lguest_hcall.h | 3 +- arch/x86/lguest/Kconfig

plain text document attachment (lguest64.patch) This is the main core code for the lguest64. Have fun, and don't hurt the puppies! Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Glauber de Oliveira Costa <glommer@gmail.com> Cc: Chris Wright <chrisw@sous-sol.org> Index: work-pv/arch/x86_64/lguest/Makefile

plain text document attachment (lguest64.patch) This is the main core code for the lguest64. Have fun, and don't hurt the puppies! Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Glauber de Oliveira Costa <glommer@gmail.com> Cc: Chris Wright <chrisw@sous-sol.org> Index: work-pv/arch/x86_64/lguest/Makefile

Kernel pages on x86 are protected by not having the _PAGE_USER bit set. When guest userspace accesses a kernel page, we didn't check this, so we'd think we'd handled the fault and return to the guest, causing the guest userspace program to loop instead of segfaulting. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> --- drivers/lguest/core.c | 2 +-

Kernel pages on x86 are protected by not having the _PAGE_USER bit set. When guest userspace accesses a kernel page, we didn't check this, so we'd think we'd handled the fault and return to the guest, causing the guest userspace program to loop instead of segfaulting. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> --- drivers/lguest/core.c | 2 +-

Christoph Hellwig said runs sparse: 1) page_tables.c unnecessary initialization 2) Change prototype of run_lguest and do cast in caller instead (when we add __user to cast, it runs over another line). Al Viro pointed out the ugly cast in push_lguest_stack(): 3) Stick with unsigned long for arg, removes 4 casts in total. Most importantly, I now realize that Christoph's incorrect ranting

Christoph Hellwig said runs sparse: 1) page_tables.c unnecessary initialization 2) Change prototype of run_lguest and do cast in caller instead (when we add __user to cast, it runs over another line). Al Viro pointed out the ugly cast in push_lguest_stack(): 3) Stick with unsigned long for arg, removes 4 casts in total. Most importantly, I now realize that Christoph's incorrect ranting

This is taken from the work I did on lguest64. When killing a guest, we read the guest stack to do a nice back trace of the guest and send it via printk to the host. So instead of just getting an error message from the lguest launcher of: lguest: bad read address 537012178 len 1 I also get in my dmesg: called from [<c0405f30>] show_trace_log_lvl+0x1a/0x2f [<c04069aa>]

This is taken from the work I did on lguest64. When killing a guest, we read the guest stack to do a nice back trace of the guest and send it via printk to the host. So instead of just getting an error message from the lguest launcher of: lguest: bad read address 537012178 len 1 I also get in my dmesg: called from [<c0405f30>] show_trace_log_lvl+0x1a/0x2f [<c04069aa>]

The assumption that we have an overall irqs_pending flags, and a one-to-one lguest <-> task mapping fails to hold on x86_64, where we can have multiple puppies, aka vcpus. Although ifdefs could be used, it makes the code much more unreadable, and other ports are on the way, anyway. So some sort of acessor is preferred anyway. Signed-off-by: Glauber de Oliveira Costa

The assumption that we have an overall irqs_pending flags, and a one-to-one lguest <-> task mapping fails to hold on x86_64, where we can have multiple puppies, aka vcpus. Although ifdefs could be used, it makes the code much more unreadable, and other ports are on the way, anyway. So some sort of acessor is preferred anyway. Signed-off-by: Glauber de Oliveira Costa

[ Ingo, Thomas cc'd in case this issue effects normal jiffies clock too? ] When the Host TSC is unreliable or can change, lguest guests use the jiffies clock. However, the clock value seems to creep upwards in sub-jiffies increments, and then tick_handle_periodic() goes into an infinite loop. Instead, the host writes the current time into the lguest page on every interrupt. This

[ Ingo, Thomas cc'd in case this issue effects normal jiffies clock too? ] When the Host TSC is unreliable or can change, lguest guests use the jiffies clock. However, the clock value seems to creep upwards in sub-jiffies increments, and then tick_handle_periodic() goes into an infinite loop. Instead, the host writes the current time into the lguest page on every interrupt. This

plain text document attachment (lguest64-device.patch) We started working a little bit on the devices for lguest64. This is still very much a work-in-progress and needs much more work. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Glauber de Oliveira Costa <glommer@gmail.com> Cc: Chris Wright <chrisw@sous-sol.org> Index:

plain text document attachment (lguest64-device.patch) We started working a little bit on the devices for lguest64. This is still very much a work-in-progress and needs much more work. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Glauber de Oliveira Costa <glommer@gmail.com> Cc: Chris Wright <chrisw@sous-sol.org> Index:

Lguest currently requires a TSC, which breaks older machines and Matt Mackall who boots the host with "notsc". In addition, there is no good solution to changing TSC speeds (informing all the guests about the TSC impending change before it happens would be a great deal of code and have issues with disobedient guests). This patch makes the host determine if the TSC is both constant and

Lguest currently requires a TSC, which breaks older machines and Matt Mackall who boots the host with "notsc". In addition, there is no good solution to changing TSC speeds (informing all the guests about the TSC impending change before it happens would be a great deal of code and have issues with disobedient guests). This patch makes the host determine if the TSC is both constant and