On 03/09/18 17:06, Brijesh Singh wrote:
> Commit:24e4ad7 (OvmfPkg: Add AmdSevDxe driver) added a driver which runs
> early in DXE phase and clears the C-bit from NonExistent entry -- which
> is later split and accommodate the flash MMIO. When SMM is enabled, we
> build two sets of page tables; first page table is used when executing
> code in non SMM mode (SMM-less-pgtable) and second page table is used
> when we are executing code in SMM mode (SMM-pgtable).
>
> During boot time, AmdSevDxe driver clears the C-bit from the
> SMM-less-pgtable. But when SMM is enabled, Qemu Flash services are used
> from SMM mode.
>
> In this patch we explicitly clear the C-bit from Qemu flash MMIO range
> before we probe the flash. When OVMF is built with SMM_REQUIRE then
> call to initialize the flash services happen after the SMM-pgtable is
> created and processor has served the first SMI. At this time we will
> have access to the SMM-pgtable.
>
> Cc: Jordan Justen <jordan.l.jus...@intel.com>
> Cc: Laszlo Ersek <ler...@redhat.com>
> Cc: Ard Biesheuvel <ard.biesheu...@linaro.org>
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Brijesh Singh <brijesh.si...@amd.com>
> ---
>
> Changes since v2:
> - rename BeforeFlashProbe() -> QemuFlashBeforeProbe()
> - add new file to define Smm specific QemuFlashBeforeProbe()
> - update commit message and comment in the code
>
> Patch is also available at
> url: github.com/codomania/edk2.git
> branch: smm-v3
>
>
> OvmfPkg/QemuFlashFvbServicesRuntimeDxe/FvbServicesSmm.inf | 2 +
> OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlash.h | 7 +++
> OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlash.c | 8 +++
> OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlashDxe.c | 12 +++++
> OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlashSmm.c | 54
> ++++++++++++++++++++
> 5 files changed, 83 insertions(+)
[ler...@redhat.com: trivial coding style improvements]:
> diff --git a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlash.c
> b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlash.c
> index 3f057918298d..462d9c0322f4 100644
> --- a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlash.c
> +++ b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlash.c
> @@ -249,7 +249,8 @@ QemuFlashInitialize (
> //
> QemuFlashBeforeProbe (
> (EFI_PHYSICAL_ADDRESS)(UINTN) mFlashBase,
> - mFdBlockSize, mFdBlockCount
> + mFdBlockSize,
> + mFdBlockCount
> );
>
> if (!QemuFlashDetected ()) {
> diff --git a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlashSmm.c
> b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlashSmm.c
> index 193fcec3690e..8999ad8d0d2b 100644
> --- a/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlashSmm.c
> +++ b/OvmfPkg/QemuFlashFvbServicesRuntimeDxe/QemuFlashSmm.c
> @@ -31,14 +31,14 @@ QemuFlashBeforeProbe (
>
> ASSERT (FeaturePcdGet (PcdSmmSmramRequire));
>
> - if (!MemEncryptSevIsEnabled()) {
> + if (!MemEncryptSevIsEnabled ()) {
> return;
> }
>
> //
> - // When SEV is enabled, AmdSevDxe runs early in DXE phase and clears the
> C-bit
> - // from the NonExistent entry -- which is later split and accommodate the
> - // flash MMIO but the driver runs in non SMM context hence it cleared the
> + // When SEV is enabled, AmdSevDxe runs early in DXE phase and clears the
> + // C-bit from the NonExistent entry -- which is later split and accommodate
> + // the flash MMIO but the driver runs in non SMM context hence it cleared
> the
> // flash ranges from non SMM page table. When SMM is enabled, the flash
> // services are accessed from the SMM mode hence we explicitly clear the
> // C-bit on flash ranges from SMM page table.
Reviewed-by: Laszlo Ersek <ler...@redhat.com>
Commit e4a1d5a7c4e4.
Thanks Brijesh!
Laszlo
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