More fallout from the writeback fixes: debug register transfer
instructions do their own writeback and thus need to disable the general
writeback mechanism.
This fixes oopses and some guest failures on AMD machines (the Intel
variant decodes the instruction in hardware and thus does not need
emulation).
Cc: Alistair John Strachan <alistair@devzero.co.uk>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
0x0f 0x01 instructions (ie lgdt, lidt, smsw, lmsw and invlpg) does
not use writeback. This patch set no_wb=1 when emulating those
instructions.
This fixes a regression booting the FreeBSD kernel on AMD.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Testing the wrong bit caused kvm not to disable nx on the guest when it is
disabled on the host (an mmu optimization relies on the nx bits being the
same in the guest and host).
This allows Windows to boot when nx is disabled on te host (e.g. when
host pae is disabled).
Signed-off-by: Avi Kivity <avi@qumranet.com>
This reverts commit a3c870bdce. While it
does save useless updates, it (probably) defeats the fork detector, causing
a massive performance loss.
Signed-off-by: Avi Kivity <avi@qumranet.com>
We add the kvm to the vm_list before initializing the vcpu mutexes,
which can be mutex_trylock()'ed by decache_vcpus_on_cpu().
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Writes that are contiguous in virtual memory may not be contiguous in
physical memory; so split writes that straddle a page boundary.
Thanks to Aurelien for reporting the bug, patient testing, and a fix
to this very patch.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>
__free_page() wants a struct page, not a virtual address.
Signed-off-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kvm mmu uses page->private on shadow page tables; so does slub, and
an oops result. Fix by allocating regular pages for shadows instead of
using slub.
Tested-by: S.Çağlar Onur <caglar@pardus.org.tr>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Allow real-mode emulation of rdmsr and wrmsr. This allows smp Windows to
boot, presumably for its sipi trampoline.
Signed-off-by: Avi Kivity <avi@qumranet.com>
The memory slot management functions were oriented against vcpu 0, where
they should be kvm-wide. This causes hangs starting X on guest smp.
Fix by making the functions (and resultant tail in the mmu) non-vcpu-specific.
Unfortunately this reduces the efficiency of the mmu object cache a bit. We
may have to revisit this later.
Signed-off-by: Avi Kivity <avi@qumranet.com>
We need to distinguish between large page shadows which have the nx bit set
and those which don't. The problem shows up when booting a newer smp Linux
kernel, where the trampoline page (which is in real mode, which uses the
same shadow pages as large pages) is using the same mapping as a kernel data
page, which is mapped using nx, causing kvm to spin on that page.
Signed-off-by: Avi Kivity <avi@qumranet.com>
Slab destructors were no longer supported after Christoph's
c59def9f22 change. They've been
BUGs for both slab and slub, and slob never supported them
either.
This rips out support for the dtor pointer from kmem_cache_create()
completely and fixes up every single callsite in the kernel (there were
about 224, not including the slab allocator definitions themselves,
or the documentation references).
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Currently, CONFIG_X86_CMPXCHG64 both enables boot-time checking of
the cmpxchg64b feature and enables compilation of the set_64bit() family.
Since the option is dependent on PAE, and since KVM depends on set_64bit(),
this effectively disables KVM on i386 nopae.
Simplify by removing the config option altogether: the boot check is made
dependent on CONFIG_X86_PAE directly, and the set_64bit() family is exposed
without constraints. It is up to users to check for the feature flag (KVM
does not as virtualiation extensions imply its existence).
Signed-off-by: Avi Kivity <avi@qumranet.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Only at the CPU_DYING stage can we be sure that no user process will
be scheduled onto the cpu and oops when trying to use virtualization
extensions.
Signed-off-by: Avi Kivity <avi@qumranet.com>
The hotplug IPIs can be called from the cpu on which we are currently
running on, so use on_cpu(). Similarly, drop on_each_cpu() for the
suspend/resume callbacks, as we're in atomic context here and only one
cpu is up anyway.
Signed-off-by: Avi Kivity <avi@qumranet.com>
By keeping track of which cpus have virtualization enabled, we
prevent double-enable or double-disable during hotplug, which is a
very fatal oops.
Signed-off-by: Avi Kivity <avi@qumranet.com>
kvm uses a pseudo filesystem, kvmfs, to generate inodes, a job that the
new anonymous inodes source does much better.
Cc: Davide Libenzi <davidel@xmailserver.org>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This patch adds an implementation to the svm is_disabled function to
detect reliably if the BIOS disabled the SVM feature in the CPU. This
fixes the issues with kernel panics when loading the kvm-amd module on
machines where SVM is available but disabled.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Protected mode code may have corrupted the real-mode tss, so re-initialize
it when switching to real mode.
Signed-off-by: Avi Kivity <avi@qumranet.com>
When writing to normal memory and the memory area is unchanged the write
can be safely skipped, avoiding the costly kvm_mmu_pte_write.
Signed-Off-By: Luca Tettamanti <kronos.it@gmail.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
When the old value and new one are the same the emulator skips the
write; this is undesirable when the destination is a MMIO area and the
write shall be performed regardless of the previous value. This
optimization breaks e.g. a Linux guest APIC compiled without
X86_GOOD_APIC.
Remove the check and perform the writeback stage in the emulation unless
it's explicitly disabled (currently push and some 2 bytes instructions
may disable the writeback).
Signed-Off-By: Luca Tettamanti <kronos.it@gmail.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
With kernel-injected interrupts, we need to check for interrupts on
lightweight exits too.
Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
If the time stamp counter goes backwards, a guest delay loop can become
infinite. This can happen if a vcpu is migrated to another cpu, where
the counter has a lower value than the first cpu.
Since we're doing an IPI to the first cpu anyway, we can use that to pick
up the old tsc, and use that to calculate the adjustment we need to make
to the tsc offset.
Signed-off-by: Avi Kivity <avi@qumranet.com>
When a vcpu causes a shadow tlb entry to have reduced permissions, it
must also clear the tlb on remote vcpus. We do that by:
- setting a bit on the vcpu that requests a tlb flush before the next entry
- if the vcpu is currently executing, we send an ipi to make sure it
exits before we continue
Signed-off-by: Avi Kivity <avi@qumranet.com>
A vcpu can pin up to four mmu shadow pages, which means the freeing
loop will never terminate. Fix by first unpinning shadow pages on
all vcpus, then freeing shadow pages.
Signed-off-by: Avi Kivity <avi@qumranet.com>
Switch guest paging context may require us to allocate memory, which
might fail. Instead of wiring up error paths everywhere, make context
switching lazy and actually do the switch before the next guest entry,
where we can return an error if allocation fails.
Signed-off-by: Avi Kivity <avi@qumranet.com>
This was once used to avoid accessing the guest pte when upgrading
the shadow pte from read-only to read-write. But usually we need
to set the guest pte dirty or accessed bits anyway, so this wasn't
really exploited.
Signed-off-by: Avi Kivity <avi@qumranet.com>
Always set the accessed and dirty bit (since having them cleared causes
a read-modify-write cycle), always set the present bit, and copy the
nx bit from the guest.
Signed-off-by: Avi Kivity <avi@qumranet.com>
