On 7 November 2018 at 14:13, Ard Biesheuvel <[email protected]> wrote: > BaseIoLibIntrinsicArmVirt was created to prevent LTO from merging > accesses to MMIO regions, resulting in instructions with multiple > output registers that KVM on ARM cannot emulate (since the exception > syndrome information that KVM relies on can only describe a single > output register) > > However, using double word loads on ARM amounts to the same thing, > and so code that relies on doing 64-bit MMIO to regions that are > emulated under KVM (such as the GICv3 TYPER register) will still > suffer from the original issue. > > So replace ldrd and strd with equivalent two instruction sequences. > > Contributed-under: TianoCore Contribution Agreement 1.1 > Signed-off-by: Ard Biesheuvel <[email protected]>
Please consider this patch with the hunk below appended > --- > MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S > b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S > index 3ad22bd5706d..0d802d6928d6 100644 > --- a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S > +++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.S > @@ -125,7 +125,8 @@ ASM_PFX(MmioWrite32Internal): > // @return The value read. > // > ASM_PFX(MmioRead64Internal): > - ldrd r0, r1, [r0] > + ldr r1, [r0, #4] > + ldr r0, [r0] > dmb > bx lr > > @@ -141,5 +142,6 @@ ASM_PFX(MmioRead64Internal): > // > ASM_PFX(MmioWrite64Internal): > dmb st > - strd r2, r3, [r0] > + str r2, [r0] > + str r3, [r0, #4] > bx lr diff --git a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm index e1a3d68a430c..deba8c1f0c59 100644 --- a/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm +++ b/MdePkg/Library/BaseIoLibIntrinsic/Arm/ArmVirtMmio.asm @@ -127,7 +127,8 @@ MmioWrite32Internal ; @return The value read. ; MmioRead64Internal - ldrd r0, r1, [r0] + ldr r1, [r0, #4] + ldr r0, [r0] dmb bx lr @@ -143,7 +144,8 @@ MmioRead64Internal ; MmioWrite64Internal dmb st - strd r2, r3, [r0] + str r2, [r0] + str r3, [r0, #4] bx lr END _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
