Previously the KVM kernel module would allocate the address range
of 0xfffbc000-0xfffbcfff for the EPT Indentity Page Tables.
A separate patch is moving that to 0xfeffc000-0xfeffcfff.
This patch updates qemu-kvm to move the VMX TSS Pages & update the
KVM BIOS code to update the E820 BIOS call memory reservations.
Previously, the VMC TSS Pages were located at 0xfffbd000-0xfffbffff.
This change moved them to 0xfeffd000-0xfeffffff.
This change also updates the KVM bios such that the E820 locations
are returned properly for these two changes.
>From a high level, these are the effects of these two changes:
Previously, the KVM would only accommodate a 256KB BIOS image. With
these changes, the BIOS image may now grow to 16MB.
Motivation for making these changes:
A larger firmware image size allows alternative BIOS images to be
used with KVM. Some possible uses are to enable UEFI firmware
or coreboot firmware. Additionally, an alternative firmware might
include a linux kernel+initrd payload, which would require several
megabytes.
Signed-off-by: Jordan Justen <jordan.l.justen@xxxxxxxxx>
---
kvm/bios/rombios.c | 8 ++++----
kvm/include/x86/asm/vmx.h | 2 +-
qemu-kvm-x86.c | 2 +-
3 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/kvm/bios/rombios.c b/kvm/bios/rombios.c
index 6186199..2d0c153 100644
--- a/kvm/bios/rombios.c
+++ b/kvm/bios/rombios.c
@@ -4596,14 +4596,14 @@ ASM_END
case 5:
/* 4 pages before the bios, 3 pages for vmx tss pages,
* the other page for EPT real mode pagetable */
- set_e820_range(ES, regs.u.r16.di, 0xfffbc000L,
- 0xfffc0000L, 0, 0, 2);
+ set_e820_range(ES, regs.u.r16.di, 0xfeffc000L,
+ 0xff000000L, 0, 0, 2);
regs.u.r32.ebx = 6;
break;
case 6:
- /* 256KB BIOS area at the end of 4 GB */
+ /* 16MB BIOS area at the end of 4 GB */
set_e820_range(ES, regs.u.r16.di,
- 0xfffc0000L, 0x00000000L ,0, 0, 2);
+ 0xff000000L, 0x00000000L ,0, 0, 2);
if (extra_highbits_memory_size || extra_lowbits_memory_size)
regs.u.r32.ebx = 7;
else
diff --git a/kvm/include/x86/asm/vmx.h b/kvm/include/x86/asm/vmx.h
index df8d4f9..99e2bb9 100644
--- a/kvm/include/x86/asm/vmx.h
+++ b/kvm/include/x86/asm/vmx.h
@@ -403,7 +403,7 @@ enum vmcs_field {
#define VMX_EPT_EXECUTABLE_MASK 0x4ull
#define VMX_EPT_IGMT_BIT (1ull << 6)
-#define VMX_EPT_IDENTITY_PAGETABLE_ADDR 0xfffbc000ul
+#define VMX_EPT_IDENTITY_PAGETABLE_ADDR 0xfeffc000ul
#define ASM_VMX_VMCLEAR_RAX ".byte 0x66, 0x0f, 0xc7, 0x30"
diff --git a/qemu-kvm-x86.c b/qemu-kvm-x86.c
index daf60b6..b5306aa 100644
--- a/qemu-kvm-x86.c
+++ b/qemu-kvm-x86.c
@@ -63,7 +63,7 @@ static int kvm_init_tss(kvm_context_t kvm)
* this address is 3 pages before the bios, and the bios should present
* as unavaible memory
*/
- r = kvm_set_tss_addr(kvm, 0xfffbd000);
+ r = kvm_set_tss_addr(kvm, 0xfeffd000);
if (r < 0) {
fprintf(stderr, "kvm_init_tss: unable to set tss addr\n");
return r;
--
1.6.0.4
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