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vmm/svm: iopm_bitmap and msr_bitmap must be contiguous in physical memory

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To achieve that the whole svm_softc is allocated with contigmalloc now.
It would be more effient to de-embed those arrays and allocate only them
with contigmalloc.

Previously, if malloc(9) used non-contiguous pages for the arrays, then
random bits in physical pages next to the first page would be used to
determine permissions for I/O port and MSR accesses.  That could result
in a guest dangerously modifying the host hardware configuration.

One example is that sometimes NMI watchdog driver in a Linux guest
would be able to configure a performance counter on a host system.
The counter would generate an interrupt and if hwpmc(4) driver is loaded
on the host, then the interrupt would be delivered as an NMI.

Discussed with:	jhb
Reviewed by:	grehan
MFC after:	2 weeks
Differential Revision: https://reviews.freebsd.org/D8321
This commit is contained in:
Andriy Gapon 2016-10-25 10:34:14 +00:00
parent 88f9a4ff75
commit 3387e8743e
1 changed files with 3 additions and 2 deletions
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5
sys/amd64/vmm/amd/svm.c
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@ -517,7 +517,8 @@ svm_vminit(struct vm *vm, pmap_t pmap)
vm_paddr_t msrpm_pa, iopm_pa, pml4_pa;
int i;
svm_sc = malloc(sizeof (struct svm_softc), M_SVM, M_WAITOK | M_ZERO);
svm_sc = contigmalloc(sizeof (*svm_sc), M_SVM, M_WAITOK | M_ZERO,
0, BUS_SPACE_MAXADDR, PAGE_SIZE, 0);
svm_sc->vm = vm;
svm_sc->nptp = (vm_offset_t)vtophys(pmap->pm_pml4);
@ -2042,7 +2043,7 @@ svm_vmcleanup(void *arg)
{
struct svm_softc *sc = arg;
free(sc, M_SVM);
contigfree(sc, sizeof (*sc), M_SVM);
}
static register_t *