On Thu, Apr 28, 2022, Manali Shukla wrote:
> Current implementation of nested page table does the page table build
> up statistically with 2048 PTEs and one pml4 entry.
> That is why current implementation is not extensible.
>
> New implementation does page table build up dynamically based on the
> RAM size of the VM which enables us to have separate memory range to
> test various npt test cases.
I'm guessing you know the drill :-)
> Signed-off-by: Manali Shukla <manali.shukla@xxxxxxx>
> ---
> x86/svm.c | 75 ++++++++++++++++-----------------------------------
> x86/svm.h | 4 ++-
> x86/svm_npt.c | 5 ++--
> 3 files changed, 29 insertions(+), 55 deletions(-)
>
> diff --git a/x86/svm.c b/x86/svm.c
> index ec825c7..e66c801 100644
> --- a/x86/svm.c
> +++ b/x86/svm.c
> @@ -8,6 +8,7 @@
> #include "desc.h"
> #include "msr.h"
> #include "vm.h"
> +#include "fwcfg.h"
> #include "smp.h"
> #include "types.h"
> #include "alloc_page.h"
> @@ -16,43 +17,32 @@
> #include "vmalloc.h"
>
> /* for the nested page table*/
> -u64 *pte[2048];
> -u64 *pde[4];
> -u64 *pdpe;
> u64 *pml4e;
>
> struct vmcb *vmcb;
>
> u64 *npt_get_pte(u64 address)
> {
> - int i1, i2;
> -
> - address >>= 12;
> - i1 = (address >> 9) & 0x7ff;
> - i2 = address & 0x1ff;
> -
> - return &pte[i1][i2];
> + return get_pte(npt_get_pml4e(), (void*)address);
> }
>
> u64 *npt_get_pde(u64 address)
> {
> - int i1, i2;
> -
> - address >>= 21;
> - i1 = (address >> 9) & 0x3;
> - i2 = address & 0x1ff;
> -
> - return &pde[i1][i2];
> + struct pte_search search;
> + search = find_pte_level(npt_get_pml4e(), (void*)address, 2);
> + return search.pte;
> }
>
> -u64 *npt_get_pdpe(void)
> +u64 *npt_get_pdpe(u64 address)
> {
> - return pdpe;
> + struct pte_search search;
> + search = find_pte_level(npt_get_pml4e(), (void*)address, 3);
> + return search.pte;
> }
>
> u64 *npt_get_pml4e(void)
> {
> - return pml4e;
> + return pml4e;
> }
>
> bool smp_supported(void)
> @@ -300,11 +290,21 @@ static void set_additional_vcpu_msr(void *msr_efer)
> wrmsr(MSR_EFER, (ulong)msr_efer | EFER_SVME);
> }
>
> +void setup_npt(void) {
Function braces go on a new line.
> + u64 end_of_memory;
> + pml4e = alloc_page();
> +
...
> diff --git a/x86/svm_npt.c b/x86/svm_npt.c
> index 53e8a90..ab4dcf4 100644
> --- a/x86/svm_npt.c
> +++ b/x86/svm_npt.c
> @@ -209,7 +209,8 @@ static void __svm_npt_rsvd_bits_test(u64 * pxe, u64 rsvd_bits, u64 efer,
> "Wanted #NPF on rsvd bits = 0x%lx, got exit = 0x%x", rsvd_bits,
> exit_reason);
>
> - if (pxe == npt_get_pdpe() || pxe == npt_get_pml4e()) {
> + if (pxe == npt_get_pdpe((u64) basic_guest_main)
> + || pxe == npt_get_pml4e()) {
The "||" should be on the previous line.
> /*
> * The guest's page tables will blow up on a bad PDPE/PML4E,
> * before starting the final walk of the guest page.
> @@ -338,7 +339,7 @@ skip_pte_test:
> get_random_bits(20, 13) | PT_PAGE_SIZE_MASK,
> host_efer, host_cr4, guest_efer, guest_cr4);
>
> - _svm_npt_rsvd_bits_test(npt_get_pdpe(),
> + _svm_npt_rsvd_bits_test(npt_get_pdpe((u64) basic_guest_main),
> PT_PAGE_SIZE_MASK |
> (this_cpu_has(X86_FEATURE_GBPAGES) ?
> get_random_bits(29, 13) : 0), host_efer,
> --
> 2.30.2
>
